„  -  .  UNWERSnTg/mlFORNIA 

1  COLLEGE  o/- MINING 

DEPARTMENTAL 
LIBRARY 


BEQUEST  OF 


SAMUELBENEDICTCHRISTY 

PROFESSOR  OF 

MINING  AND  METALLURGY 
1885-1914 


BLOWPIPE   ASSAYING 


LONDON:     1'HINTED     BY 

SPOTTISWOOUK     AND    CO.,    XEW-STUKKT     SQUAUK 
AND     PABMAJIEXT     STBKKT 


S.  B.  CHRISTY, 

PEACTICAL 

/ 

BLOWPIPE    ASSAYING 


BY 

GEORGE   ATTWOOD 
\\ 

.  S.,     ASSOC.  INST.  C.E.,     F.C.S.,     MEM.  AM.  INST.  M.E.,     ETC, 


NEW    YORK 

D.      VAN      NOSTRAND 
23    MURRAY    STREET 

1881 


/9s 


PREFACE. 


IN  publishing  this  small  volume  of  Practical  Blowpipe 
Assaying  it  is  the  wish  of  the  Author  to  record  the 
methods  of  assaying  adopted  by  himself  during  eighteen 
years  of  foreign  travel,  in  hopes  that  they  will  assist  others 
who  have  to  make  examinations  where  complete  assay 
offices  and  laboratories  are  not  to  be  found. 

Plattner's  instruments  and  apparatus  have  been  used 
as  much  as  possible ;  but,  as  the  methods  here  adopted 
have  in  so  many  instances  differed  materially  from  those 
of  Plattner  and  other  authorities  on  this  subject,  different 
apparatus  has  been  devised  to  suit  the  requirements. 

The  general  system  of  assaying  adopted  is  a  simple 
and  a  direct  one.  Sixty-four  elements  are  mentioned 
in  this  work,  and  the  assayer  may  be  asked  to  de- 
termine the  presence  of  one  or  all.  The  system  being 
a  direct  one,  directions  are  laid  down  for  the  separate 
determination  of  each.  Practice  will,  however,  soon  en- 
able the  assayer  to  determine  from  one  assay  piece  or 
sample  the  presence  of  several  elements  instead  of  one, 
and  thereby  save  time  and  labour.  For  assaying,  the 
Author  has  always  adopted  the  system  of  checking  his 
assays  by  synthetic  assays,  or,  in  other  words,  preparing 
an  assay  with  a  weighed  quantity  of  the  chemically  pure 
metal  or  element  to  be  determined,  and  mixing  it  with 


30371 fi 


vi  PKEFACE. 

materials  resembling  as  nearly  as  possible  those  of  the  ore, 
alloy,  or  compound  to  be  assayed,  and  then,  after  the 
completion  of  the  assay,  adding  to  the  direct  assay  the 
loss  found  to  have  been  incurred  in  the  synthetic. 

In  the  assay  of  gold  and  silver  alloys  a  check  assay  is 
necessary.  In  silver  assays  it  is  absolutely  necessary,  and 
by  using  the  same  most  accurate  results  can  be  obtained. 
Silver  and  gold  coins,  bars,  and  ingots  can  be  valued  or 
stamped  for  market,  and  found  to  be  correctly  assayed,  by 
following  the  methods  hereafter  described. 

,  Whilst  this  little  book  has  been  going  through  the 
press,  my  old  friend,  Professor  John  Morris,  has,  with 
his  usual  kindness  to  all  friends  of  science,  assisted  most 
materially  in  the  correction  of  the  proof  sheets  and  in  the 
revision  of  the  work,  and  to  him  the  Author  now  returns 
his  best  thanks. 

The  following  list  of  books  has  been  used  in  the 
preparation  of  this  work,  and  in  some  cases  material  has 
been  drawn  from  them. 

4,  UPPER  GLOUCESTER  PLACE,  N.W. 


BOOKS  CONSULTED  IN  THE  PREPARATION  OF 
THIS  WORK. 

'A    Manual  of    Practical   Assaying.'     By  John  Mitchell,    F.C.S. 

Edited  by  William  Crookes,  F.R.S.     London,  1873. 
'  Plattner's  Manual  of  Qualitative  and  Quantitative  Analysis  with 

the  Blowpipe.'   By  Professor  Th.  Richter.    Translated  by  H.  B. 

Cornwall,  A.M. ,  E.M.     New  York,  1873. 
'  A  Manual  of  Metallurgy.'  By  George  Hogarth  Makins,  M.R.C.S. , 

F.C.S.     London,  1873. 
'Chemical   and   Pharmaceutical    Manipulations.'       By    Professor 

Campbell  Morfit  and  Clarence  Morfit.     Philadelphia,  1857. 
'  A  Text-Book  of  Mineralogy. '     By  Edward  Salisbury  Dana.     New 

York,  1877. 
'  Manual  of  Determinative  Mineralogy. '    With  an  Introduction  on 

'Blowpipe   Analysis.'    By   Professor   George  J.  Brush.     New 

York,  1878. 
'Elements  of  Metallurgy.'    By  J.  Arthur  Phillips,  M.  Inst.  C.E., 

F.G.S.,  F.C.S.,  &c.     London,  1874. 
1  Determination  of  Minerals  by  the  Blowpipe.'     By  Dr.  C.  W.  C. 

Fuchs.     Translated  and  edited  by  F.  W.  Danby,  M.A.,  F.G.S. 

London. 
'The  Metallurgy  of  Silver  and  Lead.'      By  Robert  H.  Lamborn, 

Ph.D.     London,  1878. 
'  The  Blowpipe  :  a  Guide  to  its  Use  in  the  Determination  of  Salts 

and  Minerals.'      By  Professor  George  W.  Plympton,  C.E.,  &c. 

New  York,  1874. 
'  A  System  of  Instruction  in  Quantitative  Chemical  Analysis.'    By 

Dr.  C.  Remigius  Fresenius.     London,  1860. 
'  Manual  of   Qualitative  Chemical  Analysis.'    By  Dr.  C.  Remigius 

Fresenius.     New  York,  1864. 
'  Handbook  of  Chemistry.'     By  Professors  F.  A.  Abel  and  C.  L. 

Bloxam. 
'  Chemical  News.'     David  Forbes.     Nos.  380,  384,  392,  396,  398, 

and  412. 
'  Journal  Chemical   Society.'     May  1879.     Geo.  Attwood   on   the 

Assay  of  the  Ores  and  Compounds  of  Mercury  by  the  Blowpipe. 


CONTENTS. 


INTRODUCTION 


PAGE 

xiii 


PAET   I. 

DESCRIPTION    OF   THE   MOUTH  BLOWPIPE   AND 
APPARATUS. 


BLOWPIPE  .  .  .  . 
HOW  TO  USE  THE  BLOWPIPE 
BLOWPIPE  FUEL  .  .  . 

LAMPS 
„          FLAMES      .    .    . 

SUPPORTS    . 
„          WEIGHING      IN- 
STRUMENTS   . 


PAGE 

3 


7 

10 
12 

17 


BLOWPIPE  TOOLS,  SMALL  IM- 
PLEMENTS AND 
APPARATUS    .    22 
BATEA    .        .    .    29 
„          REAGENTS,    DRY 

AND  WET       .    32 
„          TEST   OR    PROOF 

METALS  34 


PART   II. 


Q  UA  LIT  A  TIVE  DETERMINA  TION. 


COLOURS  OF  SUBLIMATES  ON 

CHARCOAL 
POTASSIUM        .        .        .    . 

SODIUM 

C.ESIUM 

RUBIDIUM      . 

BARIUM 

STRONTIUM    . 


CALCIUM   . 

.     .    49 

43 

MAGNESIUM  . 

.     50 

45 

ALUMINIUM 

.     .     52 

46 

MANGANESE  . 

.     52 

47 

TIN    .... 

.     .     55 

47 

ANTIMONY      . 

.     55 

47 

SILVER 

5G 

48 

GOLD 

r,o 

CONTEXTS. 


PAGE                                                                                               I)AOK 

CHROMIUM 

.     .     57 

BORON 

83 

IRON 

.     57 

SILICIUM        .... 

83 

COBALT 

.     .     61 

GLUCINUM        .        .        .    . 

84 

NICKEL  . 

.     62 

LANTHANUM 

85 

ZINC 

.     63 

YTTRIUM 

C(\ 

CADMIUM 

.     65 

TERBIUM        .... 

oO 

86 

COPPER 

.     .     66 

TANTALUM        .        .        .    . 

86 

LEAD 

.     66 

URANIUM       .... 

87 

INDIUM 

.     .     68 

TUNGSTEN         .        .        .    . 

87 

BISMUTH 

.     68 

VANADIUM    .... 

88 

TITANIUM  . 

.     .     69 

PALLADIUM       .        .        .    . 

88 

MERCURY 

.     71 

RUTHENIUM 

89 

PLATINUM 

.     .     71 

CERIUM     ...        .    . 

89 

LITHIUM 

.     72 

DIDYMIUM     .... 

90 

OXYGEN     . 

.     .     73 

ERBIUM     

91 

HYDROGEN    . 

.     73 

NIOBIUM,  or  COLUMBIUM 

91 

NITROGEN 

.     .     74 

THORIUM  

'  92 

FLUORINE 

.     75 

THALLIUM      .... 

92 

CHLORINE 

.     .     75 

MOLYBDENUM  ,        .        .    . 

92 

BROMINE 

.     76 

RHODIUM       .... 

93 

IODINE 

.     .     77 

IRIDIUM    

93 

SULPHUR  .    . 

.     77 

OSMIUM  

93 

PHOSPHORUS     . 

.     .     78 

SELENIUM         .        .        .    . 

93 

ARSENIC 

.     80 

TELLURIUM    .... 

94 

CARBON 

82 

94 

PAET   III. 

ASSAY  OF  SILVER 

.     97 

ASSAY  OF  IRON        .        .    . 

159 

„        GOLD 

.     .  125 

„        NICKEL 

163 

„        MERCURY 

.  135 

„        COBALT    .        .    . 

164 

„        COPPER    . 

.     .  145 

„        NICKEL  AND    CO- 

„       LEAD   . 

.   150 

BALT 

165 

„        BISMUTH  . 

.     .  153 

„        COAL        .        .    . 

171 

TIN 

.  156 

CONTENTS. 


XI 


PAET   IV. 


PAGE 

TABLE  OF  THE  ENGLISH 
MINT  VALUE  OF  GOLD 
ACCORDING  TO  ITS  FINE- 
NESS   179 

VALUE  OF  GOLD  COINS  IN 
THE  UNITED  STATES  OF 
AMERICA  .  .191 


PAGK 

EXPLANATION  OF  AMERICAN 
GOLD  TABLE  .  .  .  192 

TABLE  OF  THE  AMERICAN 
MINT  VALUE  OF  GOLD 
ACCORDING  TO  ITS  FINE- 
NESS .  .195 


INDEX 


INTEODUGTION 


INTRODUCTION. 


XV 


IN  searching  for  and  determining  the  different  elements 
mentioned  in  the  following  tables,  the  method  adopted  is 
a  direct  examination  for  each  separate  element.  The 
beginner  will  find,  by  following  the  methods  here  de- 
scribed, that  his  task  will  be  simplified,  and  when  practice 
has  made  him  proficient  he  can  then  look  for  several 
elements  out  of  one  sample. 

Table  of  '  Metallic '  Elements  of  Commercial  Value. 


Names  of  the  Elements 

Symbols 

Atomic 
Weight 

Names  of  the  Elements 

Symbols 

Atomic 
Weight 

Potassium  . 

K 

39-1 

Chromium 

Cr 

26-7 

Sodium 

Na 

23 

Iron  . 

Fe 

28 

Csesium     « 

Cs 

133 

Cobalt 

Co 

29-5 

Rubidium  . 

Rb 

85-4 

Nickel 

Ni 

29-5 

Barium 

Ba 

68-5 

Zinc  . 

Zn 

32-6 

Strontium  . 

Sr 

43-8 

Cadmium 

Cd 

56 

Calcium 

Ca 

20 

Copper 

Cu 

31-7 

Magnesium 

Mg 

12 

Lead 

Pb 

103-5 

Aluminium 

Al 

13-5 

Indium 

In 



Manganese 

Mn 

27'5 

Bismuth 

Bi 

210 

Tin    . 

Sn 

59 

Titanium 

Ti 

25 

Antimony  . 

Sb 

122 

Mercury 

Hg 

100 

Silver 

Ag 

108 

Platinum 

Pt 

987 

Gold. 

Au 

197 

Lithium 

Li 

7 

Table  of  '  Non-Metallic  '  Elements  of  Commercial  Value. 


Names  of  the  Elements 

Symbols 

Atomic 
Weight 

Names  of  the  Elements 

Symbols 

1  Atomic 
Weight 

Oxygen 

0 

8 

Sulphur     . 

s 

16 

Hydrogen 

H 

1 

Phosphorus 

p 

31 

Nitrogen 

N 

14 

Arsenic 

As 

75 

Fluorine 

Fl 

19 

Carbon 

C 

6 

Chlorine 

Cl 

35-5 

Boron 

B 

11 

Bromine 

Br 

80 

Silicium     . 

Si 

14 

Iodine 

I 

127 

XVI 


INTRODUCTION. 


Table  of  '  Metallic '  Elements  of  No  Commercial  Value. 


Names  of  the  Elements 

Symbols 

Atomic 
Weight 

Names  of  the  Elements 

Symbols 

Atomic 

Weight 

Glucinum  . 

Be 

4-7 

Cerium 

Ce 

46 

Lanthanum 

La 

46 

Didymium 

Di 

48 

Yttrium 

Y 

— 

Erbium 

Er 

— 

Terbium    . 

Tr 

— 

Niobium    . 

Nb 

— 

Tantalum  . 

Ta 

37-6 

Thorium    . 

Th 

59-5 

Uranium    . 

U 

60 

Thallium  . 

Tl 

203 

Tungsten  . 

W 

92 

Molybdenum 

Mo 

48 

Vanadium 

V 

68-6 

Rhodium  . 

Rh 

52-2 

Palladium  , 

Pd 

53-3 

Iridium 

Ir 

99 

Ruthenium 

Ru 

52-2 

Osmium     . 

Os 

99-6 

Table  of  '  Non-Metallic  '  Elements  of  No  Commercial  Value. 


Names  of  the  Elements 

Symbols 

Atomic 
Weight 

Names  of  the  Elements 

Symbols 

Atomic 
Weight 

Selenium  . 
Tellurium  . 

Se 
Te 

39-7 
64°5 

Zirconium  . 

Zi 

44-8 

EXPLANATION  OF  THE  TEEMS  USED  IN  THE 
TABLE  OF  THE  ELEMENTS. 

Element. — One  of  the  ultimate  indecomposable  constituents  of  any 
kind  of  matter,  as  oxygen  and  hydrogen,  which  are  the  elements 
of  water. 

Atomic  Weight  is  the  weight  of  the  atom  of  an  element  as  com- 
pounded with  that  of  the  atom  of  another  element,  ascertained 
from  the  proportions  by  weight  in  which  they  combine  ;  or, 
leaving  out  of  view  the  hypothetical  idea  of  an  atom,  it  is  the 
number  expressing  the  proportions  by  weight  in  which  the 
elements  combine,  one  of  the  elements,  either  hydrogen  or 
oxygen,  being  assumed  as  the  unit  for  comparison  with  the 
others.  Oxygen  and  hydrogen  combine  to  form  water  in  the 
ratio  of  1  of  hydrogen  to  8  of  oxygen  ;  and  1  and  8  are  therefore 
the  combining  proportions  of  hydrogen  and  oxygen — also  called, 
to  avoid  hypothesis,  their  *  combining  equivalents. ' 

Symbol.  — An  abbreviation  of  the  name  of  one  of  the  elements.  Some 
of  the  abbreviations  are  taken  from  the  Latin  meaning  of  one  of 
the  words,  such  as  silver,  Ag,  from  argentum. 


xviii  INTRODUCTION. 


The  following-  elements  are  nearly  always  found  combined  with 
oxygen,  and  they  are  spoken  of  as  oxides  in  the  qualitative  determi- 
nation. For  instance,  in  the  case  of  Potassium  (page  45)  the  expres- 
sion, *  The  presence  of  potash  is  detected  by  the  blowpipe  in  two 
ways,'  is  used. 

Potassium  ....  Potash. 

Sodium       .....  Soda. 

Calcium Lime. 

Magnesium         ....  Magnesia. 

Aluminium         ....  Alumina. 

Titanium    .....  Titanic  acid. 

Lithium Lithia. 

Phosphorus        ....  Phosphoric  acid. 

Silicium     .....  Silicic  acid. 

Glucinum Glucina. 

Tantalum    .....  Tantalic  acid. 

Tungsten Tungstic  acid. 

Vanadium .....  Vanadic  acid. 

Niobium Niobic  acid. 

Thorium Thoria. 

Molybdenum      ....  Molybdic  acid. 

Zirconium Zirconia. 

The  new  earths  announced  as  occurring  in  gadolinite  and  sa- 
marsldte — as  mosandrin,  philippin,  decipin,  scandin,  holrnin,  thulin, 
samarin,  ytterbin — are  not  alluded  to  in  this  work,  as  the  characters 
of  some  of  them  are  still  a  subject  of  enquiry.  (See  Delafontaine 
Conipt  Eend.  1880.  x.  c.  221). 


PART    I. 

DESCRIPTION  OF  THE  MOUTH  BLOWPIPE 
AND  APPARATUS, 


BLOWPIPE. 

HOW   TO   USE    THE    BLOWPIPE. 

BLOWPIPE   FUEL. 

LAMPS. 

FLAMES. 

SUPPORTS. 

WEIGHING  INSTRUMENTS. 

TOOLS,  SMALL  IMPLEMENTS,  AND  APPARATUS. 

REAGENTS,  WET  AND  DRY. 

TEST  OR  PROOF  METALS. 


BLOWPIPE. 

THE  mouth  blowpipe  is  a  small  and  convenient  instrument 
by  which  a  blast  of  air  may  be  forced  through  the  flame 
produced  by  the  combustion  of  a  candle  or  lamp  fed  with 
oil  or  alcohol,  so  as  to  intensify  the  heat  of  the  blast  to 
such  an  extent  as  to  render  it  a  substitute  on  a  small  scale 
for  the  furnaces  used  in  smelting  ores  as  well  as  in 
assaying. 

It  furnishes  what  may  be  termed  a  miniature  blast 
furnace,  which  is  so  perfectly  under  control  that  the  tem- 
perature can  be  made  intense  or  mild  at  the  will  of  the 
operator;  therefore  the  many  advantages  it  affords  the 
mining  explorer,  the  chemist,  and  metallurgist  are  great. 
It  is  so  portable  that  the  little  instrument  with  all  the 
necessary  apparatus  and  reagents,  both  wet  and  dry,  re- 
quired for  qualitative  determinations  as  well  as  for  assays, 
can  be  packed  up  in  a  box  twelve  inches  square.  For 
a  rapid  determination  of  ores  and  minerals  it  has  no  qual 
and  it  possesses  in  careful  hands  most  accurate  means  of 
estimating  the  actual  percentage  of  metals  in  most  of  the 
commercial  ores. 

In  the  assay  of  gold  and  silver  alloys  the  blowpipe 
affords  the  operator  very  correct  results,  and  also  in  the 
examination  of  mineral  coals  it  is  invaluable.  Makins 
states  that  he  has  seen  a  skilful  operator  fuse  a  farthing 
(a  considerable  weight  of  copper)  by  the  blast  afforded  by 
the  lungs  alone,  and  without  fatigue. 

B  2 


BLOWPIPE  AND   APPARATUS. 


PART  I. 


Blowpipes  are  made  in  many  forms,  but  that  devised 
by  Gahn  and  recommended  by  Berzelius  may  be  con- 
sidered to  best  fulfil  all  the  requirements  for  general  use. 

It  consists  of  a  slightly  taper- 
ing tube,  fitting  into  a  cylindri- 
cal chamber  one  inch  long  and 
half  an  inch  in  diameter.  The 
chamber  serves  to  collect  any 
moisture  which  may  form  in  the 
tube  during  blowing.  Into  the 
side  of  this  chamber  a  much 
smaller  tube  in  diameter,  about 
one  inch  in  length,  is  inserted  at 
a  right  angle.  The  end  of  this 
tube  is  covered  with  a  platinum 
tip  (fig.  2)  having  a  fine  aper- 
ture. Although  silver  and  brass 
tips  answer  very  well  it  is  always 
best,  when  they  can  be  procured, 
to  employ  platinum  tips,  as  they 
are  easily  cleaned  from  soot,  &c., 
by  heating  over  the  spirit  lamp. 
The  assayer  should  be  provided 
wdth  three  or  four  tips,  the  finest 
being  used  for  qualitative  work, 
having  an  aperture  of  0*4  milli- 
metre in  diameter. 

Those  required  for  reductions 
should  have  a  larger  aperture. 
The  blowpipe  should  be  provided 
with  a  trumpet-shaped  mouth- 
piece, which  is  best  made  of  horn  or  ivory  turned  in  the 
lathe. 

The  use  of  this  mouthpiece  very  much  diminishes  the 


PART  I.  BLOWPIPE.  5 

fatigue  of  the  muscles  of  the  lips  in  long-continued  blow- 
ing, and  the  difficulty  at  first  felt  in  preventing  the  escape 
of  air  at  the  corners  of  the  mouth  is  easily  overcome  by 
practice.  The  mouthpiece  is  shown  in  the  drawing  (fig.  1). 
The  length  of  the  blowpipe  must  be  adjusted  to  the  sight 
of  the  operator,  so  that  the  test  object  may  be  held  at  such 
a  distance  as  to  be  distinctly  visible. 

HOW    TO    USE    THE    BLOWPIPE. 

The  blowpipe  is  held  firmly  in  the  right  hand  (see 
fig.  3),  and  in  such  a  manner  as  to  facilitate  a  direction  of 
the  flame  upon  the  substance  under  pro-  FIG.  3. 

cess.  The  assay  is  held  upon  a  support 
by  the  left  hand,  care  being  taken  to 
retain  the  arms  in  their  fixed  position, 
for  unsteadiness  will  prevent  an  uninter- 
rupted action  of  the  blast  on  the  assay. 
The  mouth  furnishes  the  blast,  which  derives  its  force 
from  the  muscles  of  the  cheek.  To  prevent  fatigue  of  the 
respiratory  organs,  communication  between  the  mouth 
and  chest  must  be  closed  during  the  blowing,  and  breath- 
ing maintained  through  the  nostrils.  A  few  days'  practice 
removes  all  the  difficulty  at  first  experienced  in  producing 
a  continuous  steady  current,  and  it  is  by  this  means  only 
that  proficiency  can  be  acquired.  The  operation  is  com- 
menced by  filling  the  mouth  with  air,  expanding  the 
cheeks,  and  then,  keeping  up  a  steady  forcible  pressure 
with  the  muscles,  respiration  being  allowed  to  go  on  as 
usual  through  the  nose. 

The  blowing  is  not  unhealthy,  and  with  a  little  perse- 
verance is  soon  acquired,  and  assays  made  for  several  hours 
in  succession  without  fatiguing  even  the  muscles  of  the 
cheeks. 


6  BLOWPIPE  AND  APPARATUS.  PART  I. 

Beginners  are  apt  to  imagine  that  they  must  blow 
with  considerable  force,  and  also  if  they  stop  blowing  for 
a  moment,  that  the  assay  will  be  spoiled.  In  both  these 
cases  a  little  practice  convinces  them  of  their  error,  and 
they  soon  find  that  although  the  operator  appears  to  be 
trying  to  burst  his  cheeks  in  his  efforts  to  fuse  an  assay, 
he  is  quietly  using  his  cheeks  as  a  miniature  air-bellows, 
and  not  tiring  himself  in  the  least.  A  practised  operator, 
directly  he  lays  down  his  blowpipe,  even  after  a  continuous 
blow  of  fifteen  minutes  or  more,  will  speak  to  a  com- 
panion with  ease,  without  a  single  gasp,  proving  that  the 
blowing  has  not  exhausted  his  breath. 

BLOWPIPE  FUEL. 

Pure  olive  oil  is  the  best  fuel  for  reductions  and  quan- 
titative fusions. 

Alcohol  makes  a  good  fuel  for  qualitative  work,  and  is 
especially  useful  for  the  scorification  and  cupellation  of 
silver  and  gold  alloys,  as  well  as  for  heating  glass  tubes 
and  matrasses,  and  is  employed  in  the  assay  for  mercury. 
By  adding  about  one-seventh  part  of  turpentine  to  alcohol 
the  reducing  strength  is  increased. 

Kefined  rapeseed  oil  answers  very  well  as  a  blowpipe 
fuel.  The  ordinary  illuminating  gas  makes  a  good  fuel, 
but  it  is  much  better  for  oxidation  than  for  reduction. 

The  flame  of  a  wax  candle,  or  even  the  flame  of  an 
ordinary  candle,  answers  the  purpose  when  nothing  better 
can  be  found.  Although  assays  can  be  made  from  the 
flame  supplied  by  candles,  yet  such  assays  are  generally 
attended  with  considerable  difficulty,  owing  to  the  small 
volume  of  the  flame. 

Paraffin  melted  and  poured  into  a  lamp  having  an 
open  top  and  a  broad  wick  attached  to  one  end  answers 


PART  I.  BLOWPIPE  FUEL  AND   LAMPS.  7 

nearly  all  the  purposes  required  for  blowpipe  fuel.  The 
great  objection  is  that  soot  accumulates  on  the  glass  tubes 
or  porcelain  vessels  when  heated  over  the  flame. 

In  some  countries — the  interior  of  South  America,  for 
instance — alcohol  cannot  be  procured  except  at  a  great 
cost ;  but  as  crude  spirits  made  from  sugar-cane,  &c.,  are 
generally  plentiful  in  such  places,  they  afford  the  explorer 
a  good  substitute  for  alcohol  as  well  as  oil,  owing  to  the 
presence  of  more  carbon  than  pure  alcohol  contains.  The 
spirits,  however,  contain  some  water ;  and  after  the  fuel 
is  about  one-half  consumed  it  is  best  to  empty  the  lamp 
and  fill  again  with  fresh  spirits. 

BLOWPIPE    LAMPS. 

The  form  of  blowpipe  lamp  generally  used  is  the  one 
proposed  by  Berzelius  and  used  by  Plattner  (see  fig.  4). 
The  cistern  is  made  either  of  sheet  brass  or  tinned  sheet 
iron,  about  4^  inches  long,  and  slightly  tapering  from 
1£  inch  in  width  to  1  inch  at  the  end  nearest  the  ope- 
rator, and  it  is  usually  coated  with  a  dark  lacquer. 

It  is  made  to  slide  on  a  Grerman  silver  or  brass  rod,  and 
can  be  adjusted  to  the  required  height  by  a  screw.  At 
one  end  of  the  lamp  is  an  opening  for  introducing  oil,  and  at 
the  other  is  the  wick-holder.  Roth  of  these  openings  are 
closed  by  screw  caps,  with  the  thread  cut  on  the  inside. 

The  escape  of  oil  is  prevented  by  washers  cemented  to 
the  caps  with  shell-lac  and  wax.  The  wick-holder  has 
its  greatest  breadth  at  right  angles  to  the  axis  of  the  lamp, 
and  must  be  cut  off  obliquely,  to  allow  the  flame  to  be 
directed  downwards.  Cylindrical  woven  wicks,  such  as  are 
made  for  the  Argand*burners,  are  best  adapted  for  this 
lamp,  and  they  are  pressed  flat  and  folded  lengthwise,  so 
as  to  be  introduced  fourfold. 


8  BLOWPIPE  AND  APPARATUS.  PART  I. 

The  wicks  must  not  fit  too  tightly,  and  should  be 
free  from  lime,  which  is  sometimes  used  in  the  bleaching 
of  them. 

On  the  blowpipe  stand  an  arm  is  attached,  which  has 
a  metal  ring  on  the  top,  about  If  inch  in  diameter. 

FIG.  4. 


The  arm  is  movable,  and,  like  the  cistern,  it  can  be  moved 
up  and  down,  and  it  is  kept  in  position  by  a  small  thumb 
screw.  The  ring  is  covered  with  either  a  network  of  iron 
or  platinum  wire,  and  is  used  for  holding  substances  which 
require  to  be  heated. 


PART  I. 


BLOWPIPE   LAMPS. 


The  lamp  just  described  is  best  adapted  for  burning 
oils,  but  alcohol  can  be  used  .if  required. 

A  small  glass  lamp  for  burning  alcohol  is  used  in  the 
mercury  assay  also  for  heating  substances  in  the  glass 
matrasses,  &c.  (fig.  5).  Flet-  Jm.  6.  FIG.  6. 

,    „    '  .  x  '  -,          .  (Half  size.)  (Half  size.) 

cher  (of  Warrmgton)  has  in- 

vented  a   most   useful    blow- 

pipe   lamp,    which    possesses 

the  great  advantage  of  being 

clean  and  portable,  and  it  can 

be  easily  refilled  by  melting 

solid   paraffin  and  pouring  it 

into  the  reservoir.     The  lamp 

is   constructed   of    either   tin 

or    German     silver    (fig.    6). 

The  paraffin  reservoir  is  about 

1  J  inch  in  length,  and  1  J  inch  in 

width  at  its  widest  part,  and  tapers  to  \  inch  at  the  wick 

end,  the  depth  being  about  1  inch.  The  wick  is  about  \  inch 

in  width  and  about  -f^  of  an  inch  thick,  and  is  held  in  its 

place  by  being  run  through  a  wick-holder  at- 

tached to  the  narrow  end  of  the  reservoir. 

The  reservoir  is  held  by  a  flat-bottomed 
hollow  cup  of  a  similar  form,  but  made  larger, 
so  that  when  the  lamp  has  been  used  the 
reservoir  can  be  reversed  and  packed  away 
without  injuring  the  wick  (fig.  7). 

The  reservoir  is  made  to  slide  up  and 
down  on  a  strip  of  metal  soldered  to  the  Top  View  of 


FIG. 


cup,  and  by  means  of  a  thumb  screw  it  can   Lam?'ze 
be  inclined  to  any  angle  necessary. 

For  all  ordinary  blowpipe  work  this  lamp  answers 
every  purpose,  and  it  is  one  of  the  most  convenient  and 
cleanly  lamps  that  are  in  use  at  the  present  time.  The 


10 


BLOWPIPE  AND  APPAKATUS. 


PART  I. 


FIG.  8.     (Half  size.) 


lamp  required  for  using  the  ordinary  illumination  gas  is 
of  the  simplest  description.  Brush  recommends  the 
following : — 

'  A  blowpipe  gas  lamp 
may  be  readily  made  by 
selecting  an  iron  or  brass 
tube,  8  inches  in  length 
and  f  of  an  inch  in  bore, 
bending  it  at  a  right 
angle  at  the  middle,  and 
passing  it  through  a 
block  properly  cut,  or 
placing  it  in  a  mould, 
which  is  then  filled  writh 
melted  lead.  The  top  of 
the  tube  is  then  flattened, 
and  the  proper  inclina- 
tion given  to  the  orifice 
by  filing '  (see  fig.  8). 

FLAMES    OBTAINED    BY    MEANS   OF    THE 
BLOWPIPE    BLAST. 

The  assayer  produces,  when  using  the  blowpipe,  two 
distinct  flames.  They  are  called  the  oxidising  and  re- 
ducing flames.  Practical  knowledge  of  the  way  to  create 
and  use  these  flames  is  essential,  and  until  such  know- 
ledge has  been  acquired  the  operator  cannot  proceed  in  his 
manipulations  with  safety. 

The  production  of  the  flames  can  be  acquired  in  one 
hour's  lesson,  or  from  studying  and  carrying  out  the  fol- 
lowing instructions.  Dr.  Lamborn  describes  the  blow- 
pipe flames  as  follows  : — 

'  When  we  examine  the  flame  of  a  common  candle,  we 
discover  that  it  is  composed  of  four  parts. 


PART  I. 


BLOWPIPE  FLAMES 


11 


(Half  size.) 


'  At  the  base  a  small  crescent  (fig.  9)  a  6,  with  a  clear 
blue  colour ;  higher  up,  and  in  the  centre  of  the  flame, 
the  dark  conical  portion  c ;  surrounding  this  is  FIG.  9. 
the  luminous  portion  d\  and  exterior  to  the 
last  is  the  scarcely  perceptible  mantle  /  e.  The 
student  has  to  remark  the  nature  of  two  of  these 
divisions :  the  exterior  non-luminous  part  /  e, 
which  is  composed  of  gases  already  saturated  with 
oxygen,  that  under  certain  circumstances  goes 
over  to  bodies  with  which  the  flame  is  brought 
in  contact,  and  hence  constitutes  the  oxidising 
flame ;  and  secondly,  the  luminous  portion  d, 
which  consists  of  gases  not  yet  saturated  with 
oxygen,  and  therefore  capable  of  extracting  that  element 
from  easily  reducible  oxides,  and  hence  called  the  reducing 
flame. 

'  When  the  point  of  the  blowpipe  is  held  one-third  of 

FIG.  10.     (Half  size.)  FIG.  11.     (Half  size.) 

oi   the  wick 

in  the  lamp  /** 

flame,   as  in       '  -  -      '* 
figure  10,  a 
flame  is  pro- 
duced     by 
blowing  that 

is  long,  slender,  and  blue,  which  is  hottest  at  the  outer- 
most point  a,  and  is  an  oxidising  flame.  This  action, 
however,  is  strongest  slightly  beyond  a,  about  cZ,  in  the 
stream  of  heated  gas. 

'  If  now  the  point  of  the  blowpipe  be  held  as  in  fig.  11, 
somewhat  higher  than  before,  and  not  quite  within  the 
flame,  a  larger  and  more  luminous  cone  of  burning  gases 
may  be  driven  in  'the  direction  b  c ;  within  the  bright 
portion  of  the  flame  at  a  the  above-mentioned  chemical 


12  BLOWPIPE  AND  APPARATUS.  PART  I. 

action  on  oxides  takes  place,  which  causes  this  to  be  called 
the  reducing  flame.'' 

The  most  important  matter  is  to  produce  optionally 
oxidation  or  reduction. 

Oxidation  is  very  easily  performed,  whilst  reduction 
requires  more  practice.  Berzelius  recommends  the  ope- 
rator to  take  a  small  grain  of  tin,  place  it  on  charcoal,  then 
direct  the  blowpipe  upon  it ;  it  will  soon  fuse,  and  if  the 
operator  has  not  produced  a  good  reducing  flame  it  will 
become  covered  with  a  coat  of  oxide.  The  nature  of  the 
flame  must  be  altered  until,  by  observation,  the  proper 
kind  is  produced  at  will. 

The  longer  the  button  of  tin  is  kept  bright  the  better 
and  more  expert  the  operator. 

BLOWPIPE    SUPPORTS. 

When  a  substance  has  to  be  examined  by  the  blow- 
pipe it  must  be  held  by  some  means  firmly.  The  article 
used  is  called  a  support.  A  suitable  support  should  be 
one  that  will  not  fuse  at  a  high  heat,  combine  chemically 
with  the  fused  body,  or  prevent  its  complete  heating  by 
rapid  conduction.  The  best  supports  are  charcoal  and 
platinum  wire  or  foil. 

Charcoal  makes  an  excellent  support,  as  it  is 
infusible;  it  has  great  reducing  power,  and  it  is  also 
porous,  allowing  alkalies  and  fluxes  to  pass  into  it, 
whilst  metals  and  substances  that  are  less  fusible  remain 
behind. 

Soft  pine  wood  makes  the  best  charcoal  for  blow- 
pipe work.  It  should  be  well  charred,  and  that  which 
snaps  or  smokes  in  the  fire  should  be  rejected.  '  Hard 
woods'  generally  contain  a  large  percentage  of  ash,  which 
contains  traces  of  iron  and  manganese,  and  in  some  quali- 


PART!.  BLOWPIPE   SUPPORTS.  13 

tative  determinations  the  results  are  liable  to  be  incorrect 
by  these  metals  being  absorbed  by  the  fluxes. 

Straight  pieces  free  from  knots  should  be  selected,  and 
sawed  in  the  direction  of  the  fibre  into  oblong  supports, 
about  6  inches  in  length  and  2  inches  broad. 

For  qualitative  determinations  small  pieces  of  charcoal 
answer  every  purpose ;  and  if  the  pieces  used  are  too  small 
to  be  held  by  the  hand,  they  can  be  supported  on  a  strip 
of  tin  or  thin  sheet  iron  and  the  assay  proceeded  with. 

The  saw  for  cutting  the  charcoal  should  be  a  '  cross- 
cut '  saw  with  fine  teeth,  and  a  blade  of  5  inches  in 
length,  f  of  an  inch  in  breadth,  and  -^  of  an  inch  in 
thickness.  Cavities,  deep  or  shallow,  according  to  the 
substance  to  be  examined,  are  made  by  a  borer,  or  by  the 
point  of  a  knife  in  the  charcoal,  and  the  assay  placed  in 
the  same  for  treatment. 

Oxidation,  reduction,  and  fusion  are  sometimes  so 
rapidly  performed  on  charcoal  that  the  operator  is  not 
certain  of  the  result  obtained.  In  such  cases  platinum  in 
the  form  of  foil  or  wire  is  used. 

Platinum  foil  is  best  used  in  a  narrow  strip  about 
3  inches  long  and  1  inch  broad,  and  it  is  useful  for  oxida- 
tion. 

The  substance  which  is  to  be  oxidised  is  placed  on  it, 
near  one  end,  and  heat  is  applied  by  the  blowpipe  flame 
upon  its  under  side.  The  conducting  power  of  platinum 
is  so  inconsiderable  that  the  other  end  may  be  held 
between  the  fingers  without  inconvenience. 

For  reduction  platinum  cannot  be  generally  used,  as 
it  forms  fusible  alloys  with  some  of  the  metals ;  nor 
should  sulphides,  arsenides,  or  chlorides  be  heated  in 
contact  with  it. 

Platinum  wire  should  be  about  2£  inches  long,  mode- 
rately thin,  and  bent  into  a  hook  at  one  end,  which  serves 


14  BLOWPIPE  AND   APPARATUS.  PAUT  1. 

as  the  assay  support.  The  wire  may  be  held  in  the  hand, 
either  with  or  without  a  holder,  but  the  latter  is  more 
convenient.  It  is  best  made  out  of  a  piece  of  hard  wood 
or  iron  turned ;  and,  to  prevent  injury  to  the  wires, 

FIG.  12.    (Half  size.) 


holders  are  used,  in  which  the  wire  is  inserted  into  the 
middle  of  two  slits  crossing  each  other  at  right  angles  ; 
the  latter  are  then  shut  tight  by  a  band  which  is  thrust 
over  them  and  arranged  to  screw  up  and  thus  hold  the 
wire  (see  fig.  12).  The  large  end  of  the  holder  unscrews, 
and  five  or  six  of  the  wires  can  be  kept  in  a  small  hole 
bored  in  the  handle.  The  form  used  resembles  a  crotchet- 
holder  in  nearly  every  respect. 

After  the  wires  have  been  in  use  they  can  be  cleaned 
by  warming  the  ends  in  a  test  tube  with  hydrochloric  acid, 
or  by  fusing  a  bead  of  soda  upon  it,  and  then  dissolving 
it  in  water. 

To  use  platinum  wire,  either  heat  the  hook  for  a 
moment  over  the  lamp  and  then  dip  it  into  the  flux  to  be 
used,  or  moisten  it  and  dip  in  the  flux.  Melt  the  flux 
over  the  lamp,  and  when  a  good  transparent  bead  has 
been  obtained  add  the  portion  to  be  assayed  to  it  whilst 
it  is  still  hot ;  or  if  that  is  not  practicable  moisten  the  flux 
bead  slightly  and  let  the  assay  adhere  to  it. 

Fuse  the  assay  over  the  lamp,  and  the  appearance  of 
the  bead  in  reference  to  opacity,  colour,  and  other  charac- 
teristics can  be  distinctly  seen  from  all  sides,  and  in  this 
way  are  colorations  of  the  bead  by  metallic  oxides  parti- 
cularly to  be  distinguished.  Some  fluxes  are  so  thin  that 
they  fall  through  the  loop  or  hook,  but  by  turning  the 
assay  a  few  times  the  flux  will  generally  remain  on  the  wire. 


PART  I. 


BLOWPIPE  SUPPOKTS. 


15 


Platinum  wire  cannot  be  used  when  reduction  to  the 
metallic  state  is  required. 

All  oxidation  and  reduction  experiments  in  which 
the  results  are  to  be  known  by  the  colour  of  the  fluxes 
should  be  effected  upon  platinum  wire. 


FIG.  13.     (Half  size.) 


FIG.  14.  (Half  size.) 


Platinum  spoons  are  useful  for  heating  substances 
with  bisulphate  of  potash  and  saltpetre.  Two  sizes  are 
convenient,  made  similar  to  figs.  13  and  14. 

Crucibles  and  capsules  of  fire  clay  are  made  by 
kneading  into  a  thick  paste  some  fine  FIG.  15.  (Half  size.) 
elutriated  fire  clay  and  moulding  them 
as  follows  : — 

The  crucible  mould  is  made  of  brass, 
and  consists  of  three  parts — a  plug,  a 
box  divided  into  two  parts,  and  a  stout 
ring  to  keep  the  box  together  (figs.  15 
and  16). 

Knead  with  the  fingers  some  of  the 
elutriated   fire    clay  and  make   it   into 
small  balls,  each  one  a  little  larger  than 
is  necessary  to   form   the   crucible   re- 
quired;   oil  the  inside  of  the  box  and    . 
the  end  of  the   plug ;   place   the   clay  B 
ball  in  the  box,  and  after  pressing  the 
plug  on  the  clay  give  the  plug  a  couple  Box. 

of  sharp  blows  with  a  mallet. 

The  box  in  the  meantime   must  rest  on  a  piece  of 


16 


BLOWPIPE  AND  APPAEATUS. 


PART  I. 


(Half  size.) 


hard  wood,  or  upon  an  anvil  (upon  which  has  been  pre- 
viously placed  a  piece  of  old  cloth  or  flannel).  The 
plug  is  then  removed,  and  after  that  the  ring;  the  box  is 
then  separated  easily,  and  the  crucible  is  ready  to  be 
dried.  They  should  be  dried  very  slowly  at  first,  and 
then  baked  in  an  oven,  muffle,  or  crucible. 

Capsules,  or  roasting  dishes,  or  cups,  are  made  in  a 
hard-wood  mould  (boxwood  being  generally  used)  by 
pressing  the  clay  with  a  pestle  of  the  same.  The  clay  is 
FIG.  17.  prepared  in  a  similar  manner  as  it  is  for 
moulding  the  crucibles  (fig.  17). 

Oil  both  the  mould  and  the  end  of  the 
pestle,  place  over  the  mould  a  thin  piece  of 
paper,  take  a  small  ball  of  the  elutriated 
clay,  place  it  on  the  paper,  and  then  press 
and  turn  the  pestle  round  until  the  capsule 
is  of  an  equal  thickness. 

Kemove  the  pestle,  take  the  paper  by 
two  ends,  and  lift  the  capsule  out  and  place 
it  to  dry,  the  paper  soon  falls  off,  then 
bake  as  in  the  case  of  the  crucibles. 

Open  glass  tubes,  closed  tubes,  and  bulb 
tubes,  made  of  hard  glass  free  from  lead,  are 
used  for  the  ignition  of  bodies  and  minerals  which  be- 
come volatile  at  a  high  temperature  and  deposit  a  subli- 
mate on  the  glass  tube. 

Open  glass  tubes  are  useful  when  a  substance  has  to 

FIG.  18.     (Half  size.) 


be  ignited  in  an  excess  of  air.     They  are  made  from  4 
to  6  inches  in   length,  and  from  ^  to  J  of  an  inch  in 


PART  I. 


BLOWPIPE  SUPPOETS. 


17 


/Half' 


diameter  (fig.  18),  of  hard  glass,  and  are 
easily  bent  to  the  required  angle  by 
heating  them  over  the  spirit  or  oil 
lamp. 

Closed  and  bulb  tubes  (fig.  19)  are 
employed  when  substances  require  heat- 
ing to  the  exclusion  of  air  as  much  as 
possible.  The  bulb  tube  is  especially 
serviceable  when  ores  and  rocks  have  to  be 
examined  to  see  if  they  contain  water. 

WEIGHING  INSTRUMENTS. 


A  fine,  delicate,  as  well  as  portable  assay  balance  is 
required  for  blowpipe  assays.  Mr.  L.  Oertling  -has  con- 
structed a  balance  under  the  author's  directions  which 
fulfils  all  the  requirements. 

The  balance  is  constructed  to  carry  30  grains  in  each 
pan,  and  to  turn  distinctly  with  j^-  ^  of  a  grain- 


" 


size  of  the  case  is  only  eight  inches  square  by  two  inches, 
deep.  To  prepare  the  balance  for  use,  the  front  cover, 
which  is  attached  to  the  case  by  hinges,  is  folded  back 
under  the  case,  where  it  is  held  by  two  brass  buckles, 
one  on  each  side  of  the  case.  A  stand  is  thus  formed. 
After  the  two  sockets  which  receive  the  adjusting  screws 
have  been  turned  outwards,  place  in  them  the  two  screws 
(which  will  be  found  in  the  drawers),  also  the  third 
screw,  which  fits  in  the  back  of  the  lid.  By  means  of  the 
three  screws,  assisted  by  the  two  levels  attached  to  the 
stand  inside,  the  balance  can  be  placed  in  a  horizontal 
position.  Now  hang  to  the  ends  of  the  beam  the  two 
stirrup  pans,  which  will  be  found  fixed  against  the  back 
of  the  case  in  notches,  from  which  they  can  be  removed 
by  turning  on  one  side  a  small  latch  which  moves  on  a  pin. 

c 


-6C>0{ 

^0-  6> 


18 


BLOWPIPE  AND  APPARATUS. 


PART  I. 


The  small  milled  head  button  at  the  top  of  the  stand 
may  be  removed,  and  the  fork  piece  which  holds  the  beam 
firmly  to  the  stand  (without  allowing  the  steel  knife-edge 
to  come  into  contact  with  the  agate  planes)  taken  away. 
The  handle  may  now  be  put  in  its  place,  and  the  balance 
is  ready  for  use. 

A  glass  sliding  front  is  included  in  the  balance,  which 
prevents  dust  and  currents  of  air  gaining  admission ;  also 

FIG.  20. 


If 


two  small  drawers,  in  which  are  carried  the  adjusting 
screws,  the  handle,  the  set  of  weights  and  riders ;  also  a 
small  pair  of  brass  tweezers  to  handle  the  latter.  The 
weights  are  as  follows  : — 

10  grains  I/O  grain  010  grain 


1  grain 


0-5 
0-3 
0-2 

o-i 


0-05 
0-03 
0-02 
0-01 


PART  I.  WEIGHING  INSTEUMENTS.  19 

The  riders  are  made  of  fine  gold  wire,  and  weigh  0-10 
grain.  They  are  used  to  increase  the  fine  weighing 
capacity  of  the  balance  by  placing  them  on  the  top  of 
the  beam  (which  is  graduated)  and  sliding  them  from  one 
division  to  another. 

At  each  end  of  the  beam  a  small  steel  pointer  is  fixed, 
at  the  back  of  which  are  ivory  graduated  scales.  These 
steel  pointers  help  to  indicate  the  weight  of  a  substance 
much  finer  than  the  weights  can  be  conveniently  made. 
A  pair  of  small  metal  pans  and  another  pair  made  of  horn 
complete  the  balance. 

The  horn  pans  are  used  in  weighing  ores  and  minerals, 
also  in  weighing  the  globules  obtained  in  the  mercury 


The  metal  pans  are  used  for  weighing  alloys  and  beads 
of  gold,  silver,  copper,  &c. 

For  blowpipe  assay  purposes  another  balance  is  required, 
which  will  weigh  upwards  of  30  ounces,  and  at  the  same 
time  must  be  sensitive  and  portable. 

The  author,  after  experimenting  for  several  years,  has 
at  last  succeeded  in  constructing  an  instrument  that 
answers  the  purpose  in  all  respects.  This  balance  (fig.  21) 
resembles  in  some  of  its  features  a  steelyard. 

A  brass  bar  a,  lOf  inches  in  length,  f  of  an  inch 
in  depth,  and  T\  of  an  inch  in  thickness,  represents  the 
beam.  The  beam  is  finely  polished  and  graduated.  On 
the  right-hand  side  the  graduations  represent  pounds  (Ibs.) 
and  ounces ;  on  the  left-hand  side  the  graduations  repre- 
sent fractions  of  ounces  and  grains. 

On  the  right-hand  side  there  is  a  large  movable  weight 
6,  which  can  be  clamped  at  will  by  means  of  a  small 
set  screw  c  at  the  top.  On  the  left-hand  side  there  is  a 
light  weight  d,  which  slides  smoothly  along  the  beam. 
By  sliding  the  large  weight  to  ^,  1,  H,  and  2  Ibs.  respect- 

c  2 


PART  I.  WEIGHING  INSTRUMENTS.  21 

ively,  it  shows  the  pounds  as  marked  on  the  side  of  the 
beam,  whilst  each  mark  represents  1  ounce. 

The  minor  scale  to  the  left  represents  1  ounce  in  its 
whole  graduated  length,  whilst  its  subdivisions  represent 
each  10  grains,  and  by  sliding  the  weight  to  one-half  or 
one- quarter  of  these  divisions,  5  or  2J-  grains  may  be 
weighed  by  estimation.  On  the  left-hand  end  of  the  beam 
there  is  a  weight  attached  (e)  by  means  of  a  screw ;  it 
serves  as  a  counterpoise,  also  as  a  stop  to  the  light  weight. 
On  the  right-hand  end  of  the  beam  there  is  also  a  stop  (/) 
to  prevent  the  heavy  weight  sliding  off. 

The  beam  is  provided  with  an  indicating  steel  needle 
g  and  with  a  fixed  steel  knife-edge,  which  works  in  rings 
of  hardened  steel  which  are  let  into  the  brass  part  /t,  called 
the  beam  support.  The  part  h  has  fixed  to  it  a  small 
arc,  graduated  into  ten  divisions,  by  means  of  which  the 
balance  can  be  made  to  weigh  much  closer  by  using  the 
sliding  weights. 

It  has  also  a  steel  hook,  which  enables  the  assayer  to 
suspend  the  instrument  by  means  of  a  string  or  wire  when 
he  wishes  to  weigh  any  substance  with  great  care. 

The  pan  (fig.  22)  is  made  of  brass  or  copper,  and  it  is 
about  3  inches  in  diameter  and  1  inch  deep  at  the  centre. 
The  pan  is  sustained  by  a  steel  hook  (fig.  21,  i),  which  is 
connected  with  the  short  end  of  the  beam. 

At  the  upper  end  of  the  hook  attachment  two  hard 
steel  rings  are  let  in,  upon  which  a  knife-edge  (which  is 
fixed  to  the  beam)  works.  The  hook  is  sharpened  at  the 
point,  so  that  the  assayer  can  weigh  small  sample  bags  of 
ore  or  minerals  without  using  the  pan. 

The  balance  weighs  13^  ounces,  and  with  the  pan  14^ 
ounces ;  it  is  very  portable,  and  not  liable  to  get  out  of 
repair. 

To  show  the  capabilities  of  the  balance,  the  author  has 


22  BLOWPIPE  AND  APPARATUS.  PART  I. 

recorded  the  following  experiments  which  he  has  made 
with  it : — 

Loaded  with  32  ounces  =  15,360  grains  in  the  pan,  it  turns  dis- 
tinctly on  the  addition  of  10  grains. 

Loaded  with  8  ounces  =  3,840  grains  in  the  pan,  it  turns  distinctly 
on  the  addition  of  3  grains. 

Loaded  with  4  ounces  =  1,920  grains  in  the  pan,  it  turns  distinctly 
on  the  addition  of  1  grain. 

Loaded  with  ]  ounce  =  480  grains  in  the  pan,  it  turns  distinctly 
on  the  addition  of  0'5  grain. 

Loaded  with  £  ounce  =  240  grains  in  the  pan,  it  turns  distinctly 
on  the  addition  of  0'2  grain. 

Loaded  with  £  ounce  =  120  grains  in  the  pan,  it  turns  distinctly 
on  the  addition  of  O'l  grain. 

When  the  large  and  small  sliding  weights  both  point 
to  zero  the  instrument  is  balanced.  The  readings  are 
always  taken  from  the  inner  ends  of  the  sliding  weights.1 


TOOLS,  SMALL  IMPLEMENTS,  AND  APPARATUS. 

One  hammer  for  chipping  and  breaking  rocks  and 
minerals,  for  making  cupels,  and  for  striking  the  pestle  in 
the  steel  mortar. 

Total  length  of  the  hammer,  about  10  inches;  length 
of  hammer  head,  2  J  inches,  having  a  face  about  f  of  an 

FIG.  23.     (One-quarter  size.) 


inch  square  at  one  end  and  coming  to  a  sharp  point  at 
the  other.     It  must  be  made  of  hard  steel  (fig.  23). 

1  This  ba^nce  is  made  only  by  L.  Casella,  147  Holborn  Bars,  E.G. 


PART  I.   TOOLS,  SMALL  IMPLEMENTS,  AND  APPARATUS.     23 


A  small  hammer  (fig.  24)  is  required  for  flattening 
metallic  buttons,  and  it  should  be  made  of  highly  tem- 
pered Steel  and  brightly  FIG.  24.  (One-quarter  size.) 

polished. 

A  small  steel   anvil, 
highly  polished,  about  1-J- 
by    1^  inch    and   ^  inch 
thick,  is  useful  to  flatten  metallic  beads  upon,  and  to  re- 
move slags  from  buttons  obtained  in  fusing  assays. 

To  prevent  the  buttons  flying  off  and  being  lost, 
always  wrap  them  up  in  a  piece  of  paper  before  using  the 
hammer. 

One  of  the  most  necessary  implements  used  in  pre- 
paring ores  and  minerals  for  assay  is  a  steel  mortar. 

The  mortar  consists  of  three  separate  pieces,  each  of 
which  is  smoothly  turned  and  made  of  hard  steel  (fig.  25). 

A    is    the    pestle,    B    is  FIG.  25.    (Half  size.) 

a    cylinder    in    which 

the  pestle  fits  tightly, 

and   C  is   the   mortar 

into  which  both  A  and 

B  fit. 

In  using,  place  the 
cylinder  in  the  mortar, 
then  add  the  mineral 
or  rock,  place  the  pestle  in  the  cylinder,  and  with  the 
hammer  strike  a  few  hard  blows.  (It  is  best  to  place 
the  mortar  on  some  firm  base  before  using  the  ham- 
mer.) The  mineral  will  soon  be  reduced  fine  enough  to 
be  removed  to  an  agate  mortar  for  its  final  grinding. 

An  agate  mortar  and  pestle  are  used  to  grind  to  the 
finest  powder  the  ores  for  assay,  also  to  crush  up  slags  for 
further  examination  (fig.  26). 

A  mortar  about  2  inches  in  diameter  in  the  clear  on 


24 


BLOWPIPE   AND  APPARATUS. 


PART  I. 


the  top,   and   2J  inches  on   the   outside,  and    -J   of   an 
FIG.  26.  inch  in  depth  at  the  bot- 

tom, answers   the    pur- 
pose. 

A  small  selection  of 
files  is  most  useful.  Flat, 
round,  triangular  shapes 
are  best,  and  they  should 
not  be  more  than  6 
inches  long. 

A  small  knife  and  a  pair  of  scissors  are  constantly 
needed,  and  should  be  included  with  the  other  tools. 

A  steel  magnet,  4  inches  long,  sharp  at  the  end,  like 
a  chisel,  is  used  in  the  detection  of  iron,  nickel,  &c. 

A  horn  spoon,  made  from  a  bullock's  horn,  cut,  and 
finely  scraped  in  the  inside,  so  that  it  is  perfectly  smooth, 
is  a  most  useful  addenda  to  the  assayer's  outfit.  The 
horn  is  generally  hardened  by  soaking  it  for  some  hours  in 
a  weak  solution  of  sulphate  of  iron  or  copper,  after  it  has 
been  scraped.  It  is  used  for  vanning  or  washing  ores  of 
all  kinds,  also  to  wash  slags  after  they  have  been  powdered, 

FIG.  27.     (Quarter  size.)  to  S66   if  the   Operation 

has  been  carried  on  suc- 
cessfully (see  fig.  27). 

Charcoal  borers  are 
made  of  different  sizes 
and  shapes. 
Fig.  28  represents  a  borer  used  for  boring  holes  large 

FIG.  28.    (Half  size.) 


enough    to    make    the    charcoal    furnace,    which    holds 
crucibles,  mercury  retorts,  and  roasting  cups. 


PART  I.   TOOLS,   SMALL  IMPLEMENTS,   AND   APPAEATUS.     25 

Fig.   29  represents  the  borer   mostly  used    in  mak- 
ing assays  of  silver  and  gold  FlG-  29«    (Half  size.) 
ores. 

Fig.  30  is  a  long  bore, 
the  small  end  of  which  is  used  for  boring  holes  through 
the  coal  cover  and  sides  of  the  charcoal  furnace.  The 
flat  end  is  used  for  FIG.  30.  (Half  size.) 

boring  holes  on  char- 
coal for  qualitative  de- 
terminations. 

Forceps  with   platinum   tips   are  used  to  hold  sub- 

FIG.  31.     (|  nat.  size.) 


stances  directly  in  the  blowpipe  flame  when  testing  for 
fusibility  (fig.  31). 

Brass  forceps  with  very  fine  points  are  used  to  hold 
small  objects,  such  as  the  small  silver  beads  obtained  in 
cupellation  (fig.  32). 

FIG.  32.     (Half  size.) 


Iron  forceps,  very  strong,  are  useful  in  rough  work, 
such  as  holding  a  button  of  metal  whilst  it  is  hammered  on 
the  anvil,  or  raising  and  cleaning  the  lamp  wick  (fig.  33). 

FIG.  33.    (Half  size.) 


Cutting  shears  are  used  to  clip  pieces  of  assay  silver, 
gold,  and  all  kinds  of  metals  after  they  have  been  beaten 


BLOWPIPE  AND   APPARATUS. 


PART  I. 


or  rolled  out.     They  should  be  made  of  good  steel,  and 
the  blades  kept  sharp  (fig.  34). 

FIG.  34.     (Half  size.) 


FIG.  35.    (Half  size.) 


Steel  pliers  having  fine  points,  with  jaws  slightly 
roughed  on  the  inside,  are  used  to  remove  buttons  and 

beads  from  slags  and 
cupels,  also  in  sepa- 
rating a  button  from 
slag  by  gently  press- 
ing the  substance 
after  placing  it  near 
the  inner  part  of 
the  jaw,  or  to  clean 
a  cupel  bead  the  same  way.  Good  pliers  are  often  strained 
by  placing  the  substance  to  be  pressed  too  near  the 
point  of  the  pliers  (fig.  35). 

A  magnifying  glass  composed  of  two  convex  lenses  is 
the  best,  and  it  answers  all  the  purposes  required  in  blow- 
pipe work. 

Two  small  mixing  capsules,  one  of  polished  brass,  the 
other  of  horn,  are  used  to  mix  the  powdered  mineral  with 
the  flux,  and  then  to  pour  the  charge  conveniently  into 

FIG.  36.     (Full  size.) 


assay  crucible,  roasting  cup,  or  paper  cornet  in  the 
assays  (fig.  36). 


the 


PART  I.   TOOLS,   SMALL  IMPLEMENTS,  AND  APPARATUS.     27 

A  small  ivory  spoon  is  used  to  remove  fluxes  from  the 
bottles,  and  minerals  from  the  mortar.  After  a  little  prac- 
tice it  is  not  necessary  to  weigh  many  of  the  fluxes,  as, 
the  weight  once  ascertained,  the  operator  can  judge  by 
measure  (fig.  37). 

FIG.  37.     (Full  size.) 


Two  small  wire  sieves,  one  having  1,400  holes  to  the 
square  inch  (wire  sieving),  the  other  2,000  holes  to  the 
square  inch. 

Punched  screens  will  do,  but  it  is  difficult  to  get  them 
as  fine  as  the  sieving. 

A  stand  is  necessary  to  hold  cupels  and  cupel  moulds 
for  the  cupellation  of  gold  and  silver. 

Fig.  38  represents  a  useful  form.     The  top  is  made 
of  iron,   and    is    set   in   a    wooden    stand    to     F     og 
prevent  the  heat  affecting  the  fingers  during  (Half  size.) 
the   operation.     (For   cupels,    see   p.  29  ;  for 
moulds,  see  p.  29.) 

A  small  cylinder  of  hard 
wood,  turned,  is  used  to 
prepare  the  soda  paper 
cornets  for  assays  (fig.  39). 

A  small  quantity  of  fine  iron  and  platinum 
wire  is  used  for  holding  the  small  crucibles  in 
the  furnace,  and  the  pieces  can  be  cut  and  bent 
to  suit  (fig.  40). 

The  charcoal-holder  and  furnace  is  de- 
scribed fully  in  the  mercury  assay. 

Evaporating  dishes  and  small  cups,  also  watch-glasses, 
are  necessary  when  acids  are  used.  It  is  best  to  have 


FIG.  39.    (Half  size.) 


28 


BLOWPIPE  AND   APPARATUS. 


PART  I. 


half  a  dozen  different  sizes. 

FIG.  40.     (Full  size.) 


FIG.  41.    (Half 
size.) 


Figs.  41  and  42  are  con- 
venient sizes. 

Test  tubes  for  sepa- 
rating gold  from  silver 
are  useful  (fig.  43). 

A  few  small  pipe- 
clay annealing  cups  to 
collect  the  finely-pow- 
dered gold  that  has 
been  separated  in  the 
test  tube  from  silver  by  means  of  acids  are  useful,  as 

FIG.   43.     (Half  size.) 


c 


D 


the  gold  can  be  dried  and  annealed  in  them,  and  after- 
wards removed  for  weighing  in  one  lump. 

Beaker  glasses,  a  few  small  funnels,  and  a  stand  to 
match  are  required  (fig.  44). 

FIG.  44.  FIG.  45. 


A  small  glass  wash  bottle  is  used  for  washing  preci- 
pitates, &c.  (fig.  45). 


PART  I.  TOOLS,  SMALL  IMPLEMENTS,  AND  APPAEATUS.     29 

A  small  drop  bottle  to  hold  acids  is  useful  (fig.  46). 

A  small  cupel  mould   is    used  to  FIG.  46. 

make  cupels  for  the  assay  of  gold 
and  silver  alloys,  which  are  called 
the  'previously  prepared  cupels'  (fig. 
47). 

To  make  the  above  cupels,  finely 
crushed  bone  ashes  that  have  been  previously  burnt,  so 
that  they  contain  no  animal  matter,  are  moistened,  and 
the  mould  filled  to  the  top,  FIG.  47.  (Half  size.) 

the  mould  resting  on  a  solid 
substance,  such  as  a  piece 
of  hard  wood.  The  pestle  is 
placed  on  the  top,  and  a 
few  sharp  blows  are  struck 
with  a  mallet  or  heavy  piece 
of  wood. 

The   cupel    is   removed 
and  carefully  dried.     When 
perfectly  dry,  it  should  be  smooth  at  the  top  and  show  no 
flaws  or  cracks. 

A  package  of  best  Swedish  filtering  paper  is  re- 
quired in  some  of  the  assays.  Blotting  or  some  soft 
paper,  soaked  in  a  strong  solution  of  carbonate  of  soda, 
then  dried  and  cut  into  slips  about  1J  inch  long  by  1 
inch  wide,  is  used  in  the  assay  of  silver  and  gold  ores, 
and  a  supply  should  always  be  kept  on  hand. 

The  batea  is  one  of  the  most  useful  parts  of  the 
mining  explorer  and  assayer's  outfit,  and  it  enables  the 
operator  to  make  preliminary  examinations  of  gold,  silver, 
copper,  mercury,  lead,  tin,  ores,  &c.  It  is  also  used  in 
the  assay  of  gold  and  tin  ores. 

Melville  Attwood  describes  it  as  follows :  *  Batea  is 
the  name  given  to  the  gold-washer's  bowl  or  vanning 


30 


BLOWPIPE  AND  APPARATUS. 


PART  I. 


dish,  used  in  the  placers  and  gold  mines  of  Brazil — a  small 
implement  which  affords  the  most  simple  method  of 
separating  on  a  limited  scale  the  grains  of  gold  from  the 
dirt,  sand,  pyritic  matter,  magnetic  iron,  &c.  The  form 
of  the  batea  in  common  use  in  Brazil  is  a  circular  shallow 
wooden  dish  or  bowl,  rudely  fashioned  with  an  adze  and 
chisel,  varying  considerably  in  depth  and  size,  but  never- 
theless in  practical  hands  giving  remarkable  results.' 

The  best  form  of  batea  is  represented  in  fig.  48,  and 
John  Eoach,  of  San  Francisco,  describes  it  as  c  a  disk  of 

FIG.  48.     (j_  size.) 


17  inches  diameter,  being  turned  conical  12  degrees,  will 
have  a  depth  of  1J  inch  from  centre  to  surface.  The 
thickness  may  be  J  of  an  inch.  The  outer  edge,  perpen- 
dicular to  axis,  will  require  wood  2^  inches  thick  for  its 
construction — the  best  wood,  Honduras  mahogany.' 

The  author  has  used  them  for  more  than  twenty  years, 
and  finds  that  by  taking  a  hot  iron  and  blackening  the 
wood  from  the  centre  about  H  inch  all  round  the  pecu- 
liarities of  the  separated  gold,  or  material,  are  shown 
more  distinctly  than  with  the  batea  in  its  normal  condi- 
tion as  it  comes  from  the  lathe. 


PART  I.  TOOLS,   SMALL  IMPLEMENTS,  AND   APPARATUS.     31 

To  use  the  batea  requires  practice,  and  to  describe 
the  modus  operandi  is  difficult. 

Prof.  Warington  Smyth  states  as  follows :  c  A  quantity 
of  the  material  to  be  operated  on  having  been  mingled 
and  well  stirred  by  hand  with  water  in  the  bowl,  it  is 
shaken  from  side  to  side  and  circularly  with  a  variety  of 
movements  suited  to  the  form  and  the  nature  of  the  ore, 
only  to  be  acquired  by  long  practice.  The  separation  of 
the  gold  is  partly  assisted  by  striking  one  side  of  the 
bowl  occasionally,  so  as  to  arrest  the  course  of  the  particles 
for  the  moment ;  and,  finally,  several  different  layers  or 
lines  of  mineral  matter  may  be  distinguished  from  one 
another,  the  gold  occupying  the  lower  position,  then  the 
magnetic  iron,  then  the  pyrites,  and  lastly  other  wastes.' 

Henry  Hanks  also  gives  a  very  good  description  of 
the  way  to  use  a  batea.  He  states — 

6  The  manner  of  using  the  batea  may  be  described  as 
follows  : — 

4  A  quantity  of  water  will  be  required.  This  may  be 
contained  in  a  tank  or  large  tub,  or  at  a  convenient  place 
near  the  bank  of  a  stream  or  lake. 

6  The  pulverised  ore — several  pounds  at  a  time — is 
placed  in  the  batea,  which  is  gradually  sunk  in  the  water. 
Several  times  it  is  broken  down  with,  the  fingers,  while 
the  batea  floats  on  the  water.  When  the  ore  is  thoroughly 
wet  and  formed  into  mud,  the  batea  is  taken  by-the-bye 
with  both  hands  and  again  sunk  in  the  water.  A  circular 
motion  is  then  imparted  to  it  (soon  learned  by  practice). 
The  lighter  particles  will  continuously  flow  over  the  edge 
and  sink,  while  the  heavier  ones  collect  at  the  centre. 

4  When  only  a  small  portion  remains  the  batea  may  be 
lifted,  and  the  water  held  in  the  depression  caused  to 
sweep  round  the  centre,  while  one  edge  is  slightly  de- 
pressed. 


32  BLOWPIPE  AND  APPARATUS.  PART  I. 

'  This  motion  will  gradually  remove  the  heavier  par- 
ticles toward  the  depressed  part.  If  there  is  any  gold, 
platinum,  galena,  cinnabar,  or  other  unusually  heavy  sub- 
stance, its  gravity  will  resist  the  power  of  the  water, 
while  comparatively  light  particles  move  slowly  forward. 

'  The  form  of  the  vessel  is  such  that  the  heaviest 
matter  forms  a  point,  and  can  be  closely  observed.  If 
there  is  a  particle  of  cinnabar  present  it  will  be  found  at 
the  point  of  the  prospect,  clearly  distinct  from  all  other 
substances.  The  value  of  the  batea  to  the  prospector 
cannot  be  too  highly  estimated,  and  it  should  come  into 
more  general  use.' 

Bateas  can  be  made  over  two  feet  in  diameter,  or  only 
a  few  inches.  A  portable  and  useful  size  is  about  1 7  TO 
18  inches  in  diameter. 

By  seeing  the  batea  once  used,  and  then  taking  time 
to  wash  the  first  few  samples,  the  operator  very  soon  be- 
comes an  expert  at  the  management  of  the  batea ;  and 
when  he  has  once  learned  its  use  he  will  seldom  examine 
strange  ores  without  it. 

REAGENTS  REQUIRED  FOR  BLOWPIPE 
ASSAYING. 

All  reagents  which  are  employed  in  blowpipe  investi- 
gations should  be  chemically  pure. 

Dry. 

1.  Carbonate  of  soda. 

2.  Neutral  oxalate  of  potassa. 

3.  Cyanide  of  potassium. 

4.  Borax  (biborate  of  soda). 

5.  Salt  of  phosphorus,  or  microcosmic  salt  (phosphate 
of  soda  and  ammonia). 


PART  I.   REAGENTS  REQUIRED  FOR  BLOWPIPE  ASSAYING.   33 

6.  Nitre  (nitrate  of  potash  or  saltpetre). 

7.  Bisulphate  of  potassa. 

8.  Vitrified  boracic  acid. 

9.  Protosulphate  of  iron. 

10.  Arsenic  (metallic). 

11.  Argol  (bitartrate  of  potash). 

12.  Ked  and  blue  litmus  paper. 

13.  Common  salt  (chloride  of  sodium). 

14.  Fluor  spar. 

15.  Quartz  (silicic  acid). 

16.  Graphite  (soft  lead- pencil  scrapings  answer  every 
purpose). 

17.  Sulphate  of  copper. 

18.  Magnesium  wire  (in  testing  for  phosphorus). 

19.  Caustic  potash. 

20.  Oxide  of  copper. 

21.  Oxychloride  of  lead. 

22.  Litharge  (absolutely  free  from  silver). 

23.  Finely  crushed  burnt-bone  ash. 

24.  A  small  stick  of  roll  sulphur. 

25.  Carbonate  of  ammonia. 

26.  Carbonate  of  potash. 

27.  Oxalate  of  nickel. 

28.  Chloride  of  ammonia. 

Wet. 

1.  Nitric  acid. 

2.  Nitrous  acid. 

3.  Sulphuric  acid. 

4.  Hydrochloric  acid. 

5.  Ammonia. 

6.  Nitrate  of  cobalt. 

7.  Sulphide  of  ammonium. 

The  assayer  can  purchase  all  the  above  reagents  from 
i) 


34  BLOWPIPE   AND   APPARATUS.  PART  I. 

the  chemist ;  therefore  it  is  not  necessary  to  give  any  in- 
structions in  regard  to  their  preparation. 

To  obtain  pure  metals  for  test  or  proof  purposes  to 
prove  the  assays  is  frequently  a  difficult  matter ;  therefore 
the  author  has  added  the  methods  adopted  by  himself  to 
obtain  pur«  silver,  gold,  lead,  copper,  tin,  bismuth,  mer- 
cury, and  iron. 

TEST    OB    PROOF    METALS. 
Silver. 

.  The  silver  used  for  both  qualitative  and  quantitative 
examinations  by  the  blowpipe  must  be  chemically  pure  to 
enable  the  operator  to  make  accurate  and  reliable  assays 
of  either  gold  or  silver. 

For  convenience  it  is  best  to  have  the  silver  in  two 
forms,  one  in  the  shape  of  an  ingot — say,  about  1J 
inch  long  and  ^  inch  square — the  other  should  be  in  thin 
foil,  which  latter  will  be  found  most  useful  in  the  gold 
assay. 

If  chemically  pure  silver  cannot  be  procured  from  a 
reliable  source,  such  as  a  mint,  a  first-class  laboratory, 
or  assay  office,  it  can  be  prepared  as  follows : — Dissolve 
the  purest  silver  that  can  be  obtained  in  weak  nitric  acid, 
dilute  with  water,  allow  the  solution  to  settle  for  several 
hours,  after  which  decant  carefully  and  reserve  for  use 
only  the  portions  that  are  perfectly  clear,  to  which  add  a 
solution  of  chloride  of  sodium  (common  salt)  until  the 
white  flocculent  clouds  of  chloride  of  silver  cease  to  appear. 
The  precipitation  is  then  complete.  Filter  and  wash  the 
precipitate  repeatedly  in  warm  distilled  water,  then  dry 
and  fuse  (in  a  new  and  perfectly  clean  crucible)  with  its 
own  weight  of  crystallised  carbonate  of  soda  and  about 
J  of  its  weight  of  pure  nitre.  The  heat  should  be 
applied  gently  at  first,  and  finally  raised  to  the  fusing 


PART  I,  TEST   OR  PROOF  METALS.  35 

point  of  silver,  and  when  cold  the  crucible  should  be 
broken  and  the  button  of  silver  carefully  washed.  The 
silver  must  be  again  dissolved  in  nitric  acid,  water  added, 
the  solution  allowed  to  settle,  and  great  care  taken  in 
decanting  as  before.  The  silver  is  precipitated  as  before, 
and  the  precipitate  repeatedly  washed  for  twenty-four 
hours  with  ivarm  distilled  water.  Dry,  and  again  fuse 
with  carbonate  of  soda.  If  this  process  is  carefully  carried 
out  the  silver  obtained  will  be  found  to  be  chemically 
pure. 

Gold. 

Grold  for  blowpipe  examinations  should  be  pure,  especi- 
ally for  assays  of  nickel  and  copper.  The  most  convenient 
form  will  be  found  to  be  that  of  a  thin  foil. 

If  not  procurable  it  can  be  prepared  as  follows  : — Take 
a  piece  of  gold  coin  and  fuse  it  with  three  times  its  weight 
of  silver,  and  when  in  the  state  of  fusion  pour  into  a 
vessel  containing  cold  water.  Collect  the  granulations 
thus  formed,  and  dissolve  in  a  flask  or  beaker  glass  with 
dilute  nitric  acid.  After  boiling  for  fifteen  or  twenty 
minutes  decant  carefully,  and  wash  the  gold  residue  with 
distil' ed  water;  then  attack  the  gold  with  strong  nitric 
acid  (of  1-30  specific  gravity)  for  twenty  to  thirty  minutes. 
Decant  and  wash  repeatedly  with  warm  water,  then  add 
nitro-hydrochloric  acid  and  boil  until  the  gold  is  completely 
dissolved.  Dilute  with  water,  warm  slightly,  allow  the 
solution  to  settle  for  about  twenty-four  hours,  then  decant 
and  add  oxalic  acid  slightly  in  excess.  The  mixture  of 
trichloride  and  acid  to  be  heated  gently.  The  precipitation 
is  slow,  but  is  greatly  assisted  by  heat.  When  finished, 
decant  and  wash  on  a  filter ;  afterwards  heat  over  a  gas  or 
lamp  flame  in  an  evaporating  dish  or  capsule.  The  gold 
is  easily  reduced  by  this  means  to  a  metallic  state.  Then 
fuse  with  an  addition  of  bisulphate  of  potash  and  cast  into 

D  2 


36  BLOWPIPE  AND   APPARATUS.  PART  I. 

an  ingot  or  any  other  desirable  shape.  The  gold  can  be 
beaten  or  rolled  into  thin  foil,  and  it  is  then  ready  for 
use. 

The  author  recommends  the  addition  of  bisulphate  of 
potash  as  an  extra  precaution  in  case  that  a  slight  trace  of 
silver  should  still  remain  with  the  gold  before  the  fusion. 

Lead. 

Lead  is  difficult  to  procure  entirely  free  from  silver, 
and  has  generally  to  be  prepared  by  the  operator. 

It  can  easily  be  done  by  dissolving  acetate  of  lead  in 
distilled  water  and  then  precipitating  the  lead  by  pieces 
of  metallic  zinc,  always  rejecting  the  first  portions  of  lead 
thrown  down.  The  second  portion  should  be  washed 
repeatedly  in  warm  distilled  water,  to  remove  any  acid 
still  remaining,  and  afterwards  dried  carefully  between 
pieces  of  thick  filter  paper.  The  lead  thus  obtained 
should  be  melted  on  charcoal  (in  a  hole  bored  for  the 
purpose)  by  the  blowpipe,  and  for  convenience  in  use 
some  of  it  should  be  rolled  or  beaten  out  into  thin  foil 
and  the  rest  fused  into  the  form  of  a  small  ingot.  The 
foil  is  used  to  wrap  up  the  pieces  of  gold  or  silver  alloys 
preparatory  to  cupellation.  The  ingot  shape  will  be 
found  most  suitable  for  the  following  plan,  which  the 
author  has  found  very  successful  in  the  assays  of  silver 
and  gold  ores:  i.e.  instead  of  using  granulations,  as 
generally  recommended,  take  the  ingot,  and  by  means  of 
a  small  fine  flat  file  reduce  the  lead  to  the  finest  possible 
powder. 

By  care  and  rejecting  any  large  filings  that  may  have 
been  formed,  a  6  lead  powder,'  nearly  as  fine  as  ground 
litharge,  will  be  obtained,  which  can  be  intimately  mixed 
with  the  ore  about  to  be  assayed. 

The  lead  filings  so  prepared  can  then  be  kept  in  a  small 


PART  I.  TEST   OR  PROOF  METALS.  37 

glass  bottle,  well  corked,  and  will  be  ready  for  immediate 
use. 

The  files  must  be  kept  in  a  small  case  by  themselves, 
and  never  used  on  any  other  metal  but  the  pure  lead,  else 
inaccurate  results  are  likely  to  be  obtained. 

Copper. 

The  copper  of  commerce  is  seldom  sufficiently  pure 
for  proof  purposes. 

The  following  is  the  most  convenient  mode  of  prepar- 
ing pure  copper  : — Dissolve  crystallised  sulphate  of  copper 
in  distilled  water,  and  precipitate  the  metal  by  a  clean 
ircn  plate  ;  free  the  precipitated  copper  from  the  iron  by 
boiling  with  hydrochloric  acid,  dilute  with  water,  allow  to 
settle,  then  decant  and  remove  the  precipitate  to  a  filter, 
wash  repeatedly  with  warm  water,  then  dry  and  fuse  in  a 
clean  crucible. 

When  cold,  break  the  crucible,  wash,  then  dry  and 
beat  or  roll  into  a  thin  sheet  or  foil. 

N.B.  Pure  copper  rolls  easily,  but  it  must  be  repeat- 
edly annealed  to  obtain  thin  sheets. 

Pure  copper,  especially  when  in  the  form  of  a  thin 
sheet,  should  be  cut  into  narrow  strips  and  kept  free  from 
the  atmosphere  in  a  tightly  corked  bottle. 

Tin. 

The  best  qualities  of  commercial  tin  generally  contain 
3  per  cent,  of  impurities.  Pure  tin  can  be  prepared  as 
follows : — Dissolve  good  commercial  tin  in  hydrochloric 
acid :  thus  hydrogen  will  be  evolved  and  the  metals  all 
converted  into  chlorides,  with  the  exception  of  antimony 
and  arsenic.  If  either  of  these  be  present,  it  will  combine 
with  hydrogen  and  be  evolved  as  a  gas,  viz.  as  anti- 
moniuretted  or  arsensiuretted  hydrogen,  and  some  of  the 


38  BLOWPIPE  AND  APPAKATUS.  PAST  I. 

antimony  may  also  remain  as  an  insoluble  black  residue. 
Any  residue  having  been  separated  by  nitration,  the 
liquid  is  to  be  evaporated  to  a  small  bulk  and  then  treated 
with  nitric  acid.  This  will  convert  the  tin  into  insoluble 
metastannic  acid,  a  crystalline  white  body.  The  whole  is 
now  evaporated  to  dryness,  and  then  washed  with  a  little 
hydrochloric  acid,  after  which  it  is  to  be  thrown  upon  a 
filter,  thoroughly  washed  and  dried,  and  subsequently 
reduced  by  mixing  it  with  charcoal,  and  heated  strongly 
in  a  crucible,  when  a  button  of  pure  tin  will  be  the 
result. 

The  button  of  tin  can  now  be  rolled  or  beaten  out  into 
sheets  or  foil,  and  is  ready  for  use. 

Bismuth. 

The  chief  impurities  of  commercial  bismuth  are 
sulphur,  traces  of  arsenic,  lead,  and  iron. 

The  best  method  of  purification  is  the  following:— 
Dissolve  the  crude  metal  in  nitric  acid,  and  then  concen- 
trate the  solution  by  evaporation.  Next  pour  the  clear 
solution  into  a  large  bulk  of  distilled  water.  It  will  be 
thus  decomposed,  and  a  white  sparkling  soluble  powder 
falls,  which  is  a  basic  nitrate.  This  is  to  be  removed  and 
digested  for  a  time  in  a  little  caustic  potash,  whereby  any 
arsenious  or  arsenic  acids  present  will  be  dissolved.  Next 
the  basic  nitrate  is  to  be  well  washed,  dried,  and  heated 
with  about  one-tenth  its  weight  of  charcoal  in  an  earthen 
crucible  ;  thus  the  salt  is  reduced,  and  the  bismuth  sub- 
sides in  the  pot  in  a  state  of  purity. 

The  bismuth  thus  obtained  can  be  broken  into  small 
pieces  and  placed  in  a  bottle  for  use. 

Mercury. 

The  mercury  of  commerce  is  often  adulterated  with 
lead,  tin,  zinc,  bismuth,  gold,  &c. 


PART  I.  TEST   OR  PROOF  METALS.  39 

Pure  mercury  can  be  obtained  by  the  following 
method  : — Take  about  half  a  pound  of  mercury,  place  it 
in  a  bottle  of  one-quarter  of  its  capacity,  and  add  about 
one  ounce  of  powdered  white  sugar ;  shake  vigorously  for 
a  few  moments,  then  pour  the  portion  of  mercury  that  is 
still  in  moderate-sized  globules  into  another  bottle,  add 
more  finely  powdered  sugar,  and  again  shake  for  several 
minutes  ;  then  filter  the  mercury  by  pouring  it  into  a 
small  cone  of  blotting  paper  having  its  apex  pierced  with 
a  small  pin.  The  filter  retains  the  oxides  of  foreign 
metals,  also  a  portion  of  the  mercury  that  is  in  a  very  fine 
state  of  division.  The  mercury  filters  slowly ;  but  when 
complete  remove  it  to  a  small  glass  retort,  distil  at  a 
low  temperature  very  slowly,  and  only  (Mow  about  two- 
thirds  of  the  whole  to  go  over  in  vapour.  Collect  the 
condensed  mercury  and  keep  it  for  use  in  a  bottle  with 
a  glass  stopper. 

N.B.  Mercury  that  has  been  used  in  amalgamation 
works,  even  after  having  been  distilled,  invariably  contains 
traces  of  gold  and  silver,  besides  lead,  &c.  (often  owing  to 
the  rapid  manner  in  which  it  is  volatilised  during  the  dis- 
tillation of  amalgams) ;  and  in  selecting  mercury  for 
purification  it  is  always  advisable  to  procure  some  that  has 
not  been  employed  for  such  purposes. 

Proof  mercury  should  be  tested  for  gold  by  dissolving 
it  in  nitric  acid,  and  if  any  insoluble  residue  remains  the 
mercury  is  impure  and  must  be  again  distilled  until  found 
to  be  pure. 

Iron. 

Chemically  pure  iron  is  very  difficult  to  prepare.  The 
method  used  by  Berzelius  gives  iron  of  sufficient  purity 
for  blowpipe  investigations,  and  is  the  one  generally 
adopted. 


40  BLOWPIPE  AND  APPARATUS.  PART  I. 

Clean  ordinary  iron  filings  are  taken  and  mixed  with 
about  one-fifth  their  weight  of  fine  oxide  of  iron.  The 
mixture  is  placed  into  a  refractory  crucible  and  covered 
with  a  layer  of  green  bottle  glass,  such  being  used  that  is 
free  from  oxide  of  lead.  The  whole  is  luted  up,  and 
heated  for  an  hour  to  whiteness.  In  this  way  traces  of 
carbon  and  silicon  are  oxidised  by  the  oxygen  of  the  iron 
scale,  and,  such  foreign  matters  being  removed  by  the  glass 
flux,  a  button  of  pure  iron  subsides  in  the  pot. 

The  button  thus  obtained,  after  being  cleaned  carefully, 
ean  be  used  as  a  proof,  but  it  must  be  kept  sealed  up 
from  the  air  to  prevent  oxidation. 

Piano  wire  of  different  sizes  will  be  found  not  only  of 
sufficient  purity,  but  also  a  most  convenient  form  to  use 
in  the  assay  of  lead. 


PART   II. 

QUALITATIVE  DETERMINATION. 


COLOUR    OF   SUBLIMATES    ON    CHARCOAL. 

THE  colour  of  the  sublimates  found  on  the  surface  of  a 
piece  of  charcoal  after  a  mineral  has  been  heated  in  either 
the  O.F.  or  R.F.  frequently  affords  the  assayer  a  very 
good  idea  of  the  nature  of  the  mineral  to  be  assayed. 

Charcoal  ashes  vary  in  colour,  and  care  must  be  taken 
not  to  confound  the  colour  of  the  ash  with  that  of  the 
sublimate.  For  instance,  the  ash  which  is  formed  on 
some  of  the  hard-wood  charcoal  by  the  blowpipe  blast  is 
generally  of  a  bluish  white  colour,  whilst  the  ash  obtained 
from  burning  soft-wood  or  pine  charcoal  shows  a  dullish 
or  darkish  white  colour,  and  after  cooling  scarcely  any 
colour  can  be  observed.  The  colour  of  the  hard-wood  ash, 
however,  remains  unaltered  when  cold. 

Before  heating  a  mineral  on  charcoal  apply  a  strong 
R.F.  to  a  piece  of  the  charcoal  about  to  be  used.  Note  the 
colour  of  the  ash,  and  then  heat  the  mineral  on  it.  The 
sublimate  derived  from  the  mineral  is  generally  found 
some  distance  from  the  charcoal  ash,  and  it  can  then  be 
examined  with  comparative  certainty. 

The  following  table  on  the  colours  of  sublimates  on 
charcoal,  prepared  by  D.  Forbes,  will  be  found  of  use : — 


44 


QUALITATIVE  DETERMINATION. 


PART  II. 


Colours  of  Sublimates  or  Coatings  on  Charcoal  before 
the  Blowpipe  in 

Oxidising  Flame.  Reducing  Flame. 


White  .        .        A 

1 

Greyish  white. 
Bluish  white  . 
Reddish  white 
;  Yellowish  white 
Faint  yellow  . 
Yellow    . 
Sulphur  yellow 
Lemon  yellow 
Dark  lemon  yellow 
Dark  yellow  . 
Orange  yellow 
Dark  orange  yellow 
^  Brown  yellow  . 

[  Brown     . 
Reddish  brown 

(Red          . 
Dark  red. 
1  Copper  red 
Carmine  red    . 
V  Whitish  red     . 

-  Faint  violet    . 

Te,   As,    Sb,    Zn,    Sn, 
PbS,     BiS,      NaCl, 
NH4C1,   KC1,  CdCl,J 
PbCl,    BiCl,   NaBr, 
KBr,  Nal,  KI,  11 

LiCl,  As 
Sb,  Bi,  Pb,  CuCl      . 
(Ag+Sb) 
Sn    . 
Sn,  Mo     ... 
Zn,  PbOS03      . 
Pb    . 
Bi    . 
Pb    . 
Te,  CuCl,  Cd,  In       . 
Bi,  Cd      . 
Pb,  Bi      . 
CuCl 

CuCl 
Cd   . 

Te 
Ag 
Mo 
(Sb  +  Ag+Pb) 

(Ag+Sb) 

Se     , 

Pb,  Sn,    Zn,    Mo3,   Te, 
As,  Sb,    NaS,    PbS, 
BiS,       KC1,      NaCl, 
NH4C1,  HgCl,   SbCl, 
ZnCl,     CdCl,     PbCl, 
BiCl,     SnCl,      KBr, 
NaBr,    KI,  Nal 
LiS,  LiCl,  As 
CuCl,  Sb,  Bi,  Pb 

Sn 
Sn,  Mo3 
Zn 
Pb 
Bi 
Pb 
Te,  Cd,  CuCl 
Cd 
Bi 
CuCl 

CuCl 
Cd 

Se 

3   [  Blue 


Mo3 


Iridescent 
Sa*  j  Dark  grey 
t$  (Steel  grey 


.     Cd    .        .        .        .     Cd 

.    Se,  As,  CuCl    .         .     Se,  As,  CuCl 

.     Se,  As       .         .         .     Se,  As 

The  following  give  no  sublimate  or  incrustation  in  either  flame. 


BaO,  SrO,  MgO,  A12O3,  Zr203,  YO,  ThO,  EO,  Si02,  Ce2O3,  Cr2O3, 
Di,  Fe,  Au  Ir,  Co,  Cu,  Zn,  Mn,  Ni,  Os,  Pd,  Co,  Pt,  Ru,  Ta,  Ti,  Ur, 
Vd,  Wo. 


PART  II.      COLOUK  OF  SUBLIMATES   ON   CHARCOAL.  45 

The  abbreviation  of  O.F.  for  the  oxidising  flame  and 
of  R.F.  for  the  reducing  flame  will  in  future  be  used. 

POTASSIUM. 

The  presence  of  potash  is  detected  by  the  blowpipe 
in  two  ways. 

1st.  By  the  more  or  less  intense  violet  colour  imparted 
to  the  outer  flame  when  a  substance  containing  it  is 
heated  in  the  point  of  the  blue  flame. 

2nd.  By  the  property  which  potash  has  of  producing  a 
blue  glass  when  fused  into  a  borax  bead  containing 
protoxide  of  nickel. 

In  the  first  instance  it  is  simply  necessary  to  expose  a 
small  quantity  of  the  substance  (held  in  the  loop  of  a 
platinum  wire)  to  the  point  of  the  blue  flame,  when,  upon 
fusion,  the  outer  flame  immediately  beyond  the  substance 
should  show  the  characteristic  violet  colour. 

This  reaction,  however  characteristic  in  the  case  of 
tolerably  pure  potash  salts,  as  the  carbonate,  nitrate, 
sulphate,  chloride,  bromide,  iodide,  and  cyanide,  is  very 
easily  interfered  with. 

Phosphates  and  borates  of  potash  do  not  give  it,  and 
even  a  small  percentage  of  soda  renders  it  invisible  in 
the  overpowering  yellow  reaction. 

When  lithia  is  present  it  is  .easily  obscured  by  the 
more  intense  red  flame  due  to  that  alkali.  In  very  few- 
silicates  is  this  reaction  of  value,  as  most  of  them  contain 
more  or  less  soda ;  and  even  when  they  are  quite  free  from 
soda  the  reaction  is  generally  too  indistinct,  and  particu- 
larly so  in  the  more  infusible  ones. 

In  employing  the  second  method  the  loop  of  a  platinum 
wire  is  filled  up  with  a  fused  globule  of  borax  glass,  to 
which  a  small  quantity  of  boracic  acid  has  been  added. 
Sufficient  protoxide  of  nickel  (oxalate  of  nickel  is  the 


QUALITATIVE  DETEKMINATION".  PART  IT. 

best  salt  to  use)  is  now  dissolved  in  it,  so  as  to  make  the  glass 
bead,  when  cold,  appear  of  a  brownish  colour.  This  globule 
is  now  melted  in  the  oxidising  flame  along  with  the  sub- 
stance supposed  to  contain  potash,  and  when  perfectly 
cold  is  examined  to  see  if  it  has  changed  its  original 
brown  colour  to  a  more  or  less  blue  tint.  If  no  potash  is 
present,  or  too  little  of  the  substance  has  been  dissolved 
in  the  glass,  the  colour  will  be  unchanged ;  but  if  sufficient 
of  the  substance  has  been  employed,  and  it  was  not  too 
poor  in  potash,  then  the  glass  bead  will  be  found  to 
possess  a  blue  tint,  not  unlike  that  of  a  weak  solution  of 
oxide  of  nickel  in  ammonia. 

As  the  colour  of  the  glass  is  unchanged  when  smaller 
quantities  of  potash  are  present,  this  method  is  of  little 
use  in  the  examination  of  most  silicates,  and  the  deter- 
mination must  be  left  to  spectroscopic  examination  or  to  a 
chemical  analysis. 

SODIUM. 

When  soda  is  fused  in  the  point  of  the  blue  flame,  the 
outer  flame  is  coloured  strongly  yellow,  or  rather  reddish 
yellow. 

This  property  affords  an  excellent  test  for  detecting 
the  presence  of  soda  in  its  compounds,  as  it  is  only 
necessary  to  heat  a  splinter  (in  the  platinum  forceps,  or 
in  the  loop  of  a  perfectly  clean  platinum  wire)  in  the 
point  of  the  blue  flame,  when,  if  soda  is  present,  the  outer 
flame  will  be  seen  to  enlarge  itself  and  be  coloured  reddish 
yellow. 

This  test  is  extremely  sensitive.  It  is  applicable  to 
silicates  and  the  more  infusible  compounds,  and  it  is  not 
interfered  with  by  the  presence  of  considerable  quantities 
of  potash  or  lithia. 

When  potash  is  present  in  much  greater  quantity  than 


PART  II.      SODIUM,  CESIUM,  RUBIDIUM,  AND   BARIUM.       47 

the  soda,  provided  no  phosphoric  or  boracic  acid  is 
present,  the  outer  flame  nearest  the  assay  is  tinged  more 
or  less  violet,  but  farther  off  shows  only  the  soda  yellow. 
If  lithia  is  present  the  flame  will  be  of  a  more  or  less 
reddish  yellow,  or  yellowish  red  colour,  in  proportion  to  the 
greater  or  less  amount  of  lithia  contained  in  the  substance 
under  examination. 

CJESIUM. 

Cassia  is  a  rare  alkali ;  and  although  its  volatile  salts 
communicate  a  violet  colour  to  the  flame,  its  determination 
cannot  be  effected  with  certainty  by  the  blowpipe,  and  it 
must  be  examined  by  the  spectroscope.  The  spectrum 
of  caesium  characterises  the  element  with  certainty,  its 
pale  blue  lines  being  very  brilliant  as  well  as  distinct. 

RUBIDIUM. 

Rubidia,  like  csesia,  is  a  rare  alkali,  found  generally  in 
mineral  waters.  It  gives  a  violet  colour  to  the  flame,  but 
the  definite  determination  must  be  referred  to  the  spectro- 
scope. Its  splendid  indigo  blue  lines,  as  shown  by  the 
above  instrument,  are  most  prominent  as  well  as  charac- 
teristic. 

BARIUM. 

Baryta  and  its  compounds,  when  fused  in  the  point  of 
the  blue  flame,  communicate  more  or  less  an  intense 
yellowish  green  colour  to  the  outer  flame.  When  mois- 
tened with  a  very  weak  solution  of  nitrate  of  cobalt  and 
fused  in  the  O.F.,  it  gives  a  light  brown  bead.  With  a 
strong  solution  it  gives  a  brown  or  brick  red  bead,  which 
loses  its  colour  on  cooling,  and  on  exposure  to  air  breaks 
up  to  a  faint  grey-coloured  powder. 


48  QUALITATIVE  DETERMINATION.  PART  II. 

On  charcoal  alone  the  hydrate  fuses,  boils,  swells  up, 
and  is  absorbed  by  the  charcoal. 

With  soda  on  charcoal  baryta  fuses  and  is  absorbed. 
( )n  charcoal  alone  the  carbonate  of  baryta  fuses  easily  to 
a  clear  glass,  which  becomes  enamel  white  on  cooling,  and 
if  longer  heated  become  caustic,  boils  up,  and  is  absorbed. 
With  borax  on  platinum  wire  baryta  dissolves  to  a  clear 
glass,  which,  if  sufficiently  saturated,  can  be  flamed  to  a 
white  enamel.  If  supersaturated  the  glass  becomes  of 
itself  enamel  white  on  cooling.  With  salt  of  phosphorus 
the  reactions  are  the  same  as  with  borax.  In  silicates, 
either  natural  or  artificial,  the  blowpipe  is  altogether 
inefficient  to  detect  the  presence  of  baryta  without  the 
assistance  of  humid  analysis. 

STRONTIUM. 

The  compounds  of  strontium,  when  heated  in  the  point 
of  the  blue  flame,  colour  the  outer  flame  purple  red.  When 
much  baryta  is  present  this  coloration  is  obscured  by  the 
yellow  green  due  to  baryta.  When  a  soluble  strontia 
salt  is  dissolved  in  strong  alcohol  and  the  solution  burnt 
alone,  or  on  a  small  piece  of  cotton  wool  attached  to  a 
platinum  wire,  the  purple  red  coloration  of  the  flame  is 
seen.  In  some  cases  a  few  drops  of  hydrochloric  acid  are 
previously  added,  which  forms  a  chloride  and  colours  the 
flame  more  intensely.  But  if  it  is  a  sulphate  of  strontia 
subject  it  to  a  K.F.  on  charcoal  (forming  a  sulphide) ;  then 
treat  it  with  acid  and  alcohol,  which  will  give  an  intense 
red  flame. 

The  hydrate,  when  heated  on  charcoal,  boils  up  in  its 
water  of  crystallisation,  solidifies,  and  again  fuses  with 
violence,  and  is  absorbed  by  the  charcoal. '  The  carbonate 
only  fuses  at  its  edges  and  effloresces  at  the  same,  and  it 
is  reduced  to  strontia,  giving  a  strong  light  and  colouring 


TART  II.  STRONTIUM   AND   CALCIUM.  49 

the  reducing  flame  red,  and  on  cooling  reacts  alkaline  for 
test  papers. 

The  red  coloration  of  strontia  is  so  much  stronger 
than  that  produced  by  lime,  that  a  small  quantity  of 
strontia  can  be  detected  in  aragonite  (carbon  dioxide  44 
and  lime  56  =  100).  The  mineral  must  be  previously 
decrepitated,  then  heated  in  the  blue  flame  (it  does  not 
fuse).  It  will  soon  be  observed  that  the  flame  is  coloured 
more  red  than  it  would  be  by  an  equally  large  piece  of  calc 
spar. 

When  testing  the  carbonate  or  sulphate,  the  flame  is 
often  noted  to  be  first  yellowish,  but  afterwards  purple 
red  is  seen. 

CALCIUM. 

Lime,  when  heated  in  the  point  of  the  blue  flame, 
communicates  to  the  outer  flame  a  weak  red  colour,  much 
fainter  than  that  produced  by  strontia.  In  its  compounds 
this  colour  is  more  or  less  mixed  with  yellow.  In  the 
case  of  carbonates  it  is  at  first  yellow,  and  later  on,  as  the 
carbonic  acid  is  driven  off,  it  becomes  red.  The  sulphate, 
chloride,  and  fluoride  all  give  this  reaction. 

The  presence  of  barytes  or  soda  in  any  quantity 
obscures  this  test,  which  is  also  not  visible  in  the  com- 
pounds of  lime  with  phosphoric,  arsenic,  boracic,  titanic, 
and  tungstic  acids ;  and  amongst  silicates  (wollastonite, 
silica  51*7,  lime  48*3  =  100)  stands  alone  in  producing 
a  faint  reddish  flame  before  the  blowpipe,  due  to  the  pre- 
sence of  lime. 

Before  the  blowpipe  lime  is  unchanged ;  the  carbonate 
becomes  caustic,  and  at  the  same  time  it  appears  strongly 
illuminated  by  the  flame,  and,  if  in  pieces,  slacks  and  falls 
to  powder  when  moistened,  and  reacts  alkaline.  With 

E 


50  QUALITATIVE  DETERMINATION.  PART  II. 

borax  it  dissolves  easily  to  a  clear  glass,  which  becomes 
opaque  on  flaming.  When  the  glass  is  saturated  it 
crystallises  on  cooling,  and  loses  its  round  form,  but  in  no 
case  does  it  become  as  white  as  the  glass  from  baryta  or 
strontia. 

With  soda  on  charcoal  it  is  not  affected  ;  the  soda,  being 
absorbed  by  the  charcoal,  leaves  the  lime  behind. 

With  nitrate  of  cobalt  it  is  infusible  and  acquires  a 
greyish  colour. 

When  lime  is  associated  with  baryta  or  strontia,  as 
sometimes  in  heavy  spar,  strontianite,  baryta,  &c.,  the 
powdered  substance,  when  treated  with  soda  on  charcoal, 
leaves  the  lime  and  oxides  of  iron  on  the  charcoal  surface, 
whilst  the  other  substances  sink  into  the  charcoal. 

In  silicates  little  dependence  can  be  placed  on  re- 
actions for  lime,  but  in  general  the  presence  of  lime  may 
be  suspected  by  the  following  tests : — 

1st.  The  swelling  or  frothing  up  in  testing  for  fusibi- 
lity. 

2nd.  Keactions  with  borax  and  salt  of  phosphorus 
prove  that  silicates  containing  lime  dissolve  easily, 
and  with  salt  of  phosphorus  alone  the  silica  is 
separated,  and  the  glass  on  cooling  is  in  most  cases 
opalescent. 

3rd.  With  a  small  quantity  of  soda  it  fuses  to  a  glo- 
bule, but  with  more  soda  it  gives  a  slaggy  mass. 
It  is  best,  however,  to  employ  the  humid  process. 

MAGNESIUM. 

Before  the  blowpipe  magnesia  does  not  give  any  sen- 
sible colorations  to  the  flame,  and  it  remains  unchanged. 
The  carbonate  is  decomposed  by  the  heat  and  becomes 
more  luminous  and  reacts  alkaline  to  test  papers. 


FALT  II.  MAGNESIUM.  51 

With  borax  magnesia  is  easily  soluble  to  a  clear  bead, 
which  can  be  flamed  opaque,  and  after  saturation  gives 
on  cooling  a  crystalline  glass,  but  less  so  than  lime. 

It  is  easily  soluble  in  salt  of  phosphorus,  forming  a 
clear  glass,  rendered  opaque  by  flaming,  and  if  fully  satu- 
rated the  glass  becomes  milk  white  on  cooling. 

With  soda  on  charcoal  the  soda  sinks  into  the  charcoal, 
leaving  the  magnesia  unchanged. 

With  nitrate  of  cobalt  it  acquires  a  flesh-red  colour, 
which  is  best  seen  when  entirely  cold.  The  phosphates  of 
magnesia  melt  and  give  a  violet  red  colour  on  similar  treat- 
ment. 

Native  magnesia  (periclase  or  magnesium  oxide),  the 
hydrate  (brucite,  magnesia  69,  water  31  =  100),  the  car- 
bonate (magnesite,  carbon  dioxide  52*4,  magnesia  47*6 
=  100),  and  hydromagnesite  (carbon  dioxide  36*3,  mag- 
nesia 43*9,  wTater  19*8  =  100),  and  in  Epsom  salts 
(epsomite,  sulphur  trioxide  32*5,  magnesia  16'3,  water 
f51'2  =  100),  the  above  reactions  are  sufficiently  charac- 
teristic to  decide  the  presence  of  magnesia  if  the  mine- 
rals in  question  are  free  from  other  colouring  metallic 
oxides ;  but  in  nearly  all  the  other  metallic  compounds  the 
wet  way  must  be  resorted  to,  except  in  cases  where  the 
physical  properties  or  chemical  reactions  of  the  other 
constituent  of  the  mineral  in  question  .give  a  clue  to  its 
identity. 

Zehmen  gives  the  following  method  for  distinguishing 
ordinary  limestones  from  dolomite  or  magnesian  limestone 
(which  is  often  a  question  of  interest).  A  quantity  of  the 
finest  possible  powder  is  placed  in  a  small  depression  on  pla- 
tinum foil,  or  a  platinum  spoon,  and  heated  several  minutes 
strongly  to  a  thorough  red  heat.  Ordinary  limestone  on 
cooling  sinters  together  slightly,  and  can  be  turned  out  of 
the  platinum  without  breaking  up  if  handled  carefully, 

E  2 


52  QUALITATIVE   DETERMINATION.  PART  II. 

and  it  often  shows  a  tendency  to  adhere  to  the  platinum, 
and  therefore  it  requires  a  little  assistance  to  detach  it. 

Dolomite  (calcium  carbonate  54*35,  magnesium  car- 
bonate 45*65  =  100),  on  the  contrary,  does  not  sinter  after 
heating,  but  falls  to  pieces,  forming  a  still  more  porous 
and  light  powder,  and  many  dolomites  even  on  heating 
swell  up  from  the  fact  that  the  gas  frequently  carries  off 
traces  of  the  powder  with  the  flame. 

ALUMINIUM. 

Alumina  in  both  the  oxidising  and  reducing  flames 
remains  unchanged.  With  borax  it  dissolves  slowly,  form- 
ing a  clear  glass,  which  is  not  rendered  turbid  on  flaming, 
nor  does  it  become  so  on  cooling.  If  a  large  quantity  is 
added  to  the  glass  in  the  state  of  the  finest  powder  it  is 
rendered  opaque,  and  on  cooling  the  surface  becomes 
crystalline  and  is  almost  infusible.  With  phosphate  salt 
it  is  dissolved  to  a  clear  glass,  which  remains  so.  A  very 
large  quantity  renders  the  glass  semitransparent. 

With  soda  on  charcoal  it  swells  up  a  little  and  gives 
an  infusible  product,  whilst  the  excess  of  soda  is  absorbed 
by  the  charcoal.  With  nitrate  of  cobalt  and  a  high  tem- 
perature it  gives  a  fine  blue  compound,  the  colour  of  which 
is  most  intense  when  cold. 

In  minerals  which  contain  no  colouring  metallic  oxide 
the  blue  furnished  by  the  action  of  nitrate  of  cobalt  gives 
a  very  good  test  for  alumina. 

MANGANESE. 

The  oxides  are  infusible  both  in  the  O.F.  and  R.F., 
and  they  leave  on  the  charcoal  the  red  oxide,  which  has  a 
reddish  brown  colour. 


PART  II.  MANGANESE.  53 

With  borax  the  oxide  is  dissolved  in  the  O.F.,  forming 
a  glass  which  is  of  an  amethyst  violet  colour  when  hot, 
and  when  cold  a  reddish  violet.  If  too  much  mineral 
is  treated  the  glass  may  appear  quite  black,  as  the  above 
colour  is  very  intense,  and  even  opaque,  unless  pressed 
flat  or  drawn  out  by  the  forceps.  In  the  E.F.  this  co- 
loured glass  becomes  colourless,  and  if  very  dark  it  is  best 
reduced  on  charcoal  by  the  addition  of  a  little  tin. 

With  phosphate  glass  in  the  O.F.,  if  much  manganese 
is  dissolved,  the  glass,  when  hot,  is  brownish  violet,  and 
when  cold  it  is  reddish  violet,  but  it  never  becomes 
opaque.  If  the  glass  contains  but  little  oxide  and  in 
nearly  colourless,  the  addition  of  a  little  nitre  will  bring 
out  the  colour. 

On  charcoal  with  soda  in  E.F.  the  oxide  is  not  reduced, 
and  remains  behind  whilst  the  soda  is  absorbed  by  the 
charcoal.  In  O.F.  on  platinum  wire  or  foil  wTith  soda,  when 
too  much  oxide  is  not  used,  a  transparent  green  mass  is 
formed  (manganite  of  soda),  which  on  cooling  becomes 
bluish  green  and  opaque. 

In  substances  which  do  not  contain  metals  giving 
coloured  beads  with  borate  and  phosphate  salts  in  O.F. 
and  K.F.  manganese  is  very  easily  detected  by  its  be- 
haviour with  the  above  reagents,  the  former  of  which 
gives  a  much  more  intense  colour.  If  other  colour- 
ing metals  are  present  in  small  quantities  they  do  not 
have  much  influence  on  the  amethyst  colour  seen  in  the 
O.F.  bead,  but  in  the  reduction  bead  show  their  colours 
(for  example,  iron  oxides)  distinctly,  as  the  manganese 
colour  has  disappeared.  If  much  iron  oxide  is  present  the 
bead  will  appear  in  the  O.F.  blood  red,  and  after  the  R.F. 
action  yellow. 

In  case  the  manganese  present  is  so  small  that  it  does 
not  colour  the  phosphate  beads,  a  small  crystal  of  nitre  is 


54  QUALITATIVE   DETERMINATION.  PART  II. 

placed  in  a  porcelain  capsule,  and  the  phosphate  bead, 
having  been  made  to  take  up  as  much  as  possible  of  the 
substance  under  examination  in  the  O.F.,  is,  whilst  fused, 
quickly  brought  into  contact  with  the  crystal  of  nitre, 
which  causes  the  glass  to  swell  up,  and  it  is  seen  at  the 
point  of  contact  to  tint  the  froth  an  amethyst  or  rose- 
red  colour  the  instant  after  cooling,  an  effect  due  to  the 
formation  of  manganite  of  potash  at  the  point. 

If  a  substance  is  mixed  with  other  volatile  oxides,  but 
contains  above  0*1  per  cent,  of  oxide  of  manganese,  it 
should  be  brought  to  the  finest  powder  and  mixed  with 
two  or  three  times  its  bulk  of  soda,  then  melted  in  O.F. 
on  platinum  foil ;  the  soda  forms  manganate  of  soda, 
having  a  transparent  green  colour,  more  so  when  hot,  but 
a  bluish  green  on  cooling.  Even  with  less  than  0*1  per 
cent.,  by  using  two  parts  soda  and  one  part  nitre  instead 
of  soda  alone,  the  manganese  is  more  completely  oxidised 
and  tints  the  mass  bluish  green  when  cold. 

If  chrome  was  present  the  yellow  chromate  of  soda 
would  give  a  yellow  tint ;  this,  however,  would  not  destroy 
the  tjst,  which  may  even  be  used  for  finding  a  trace  of 
manganese  in  oxide  of  chromium ;  the  colour  is,  however, 
when  cold,  yellowish  green  instead  of  bluish  green. 

To  employ  these  tests  with  metallic  alloys  they  must 
first  be  oxidised  by  roasting,  action  of  acids,  or  deflagration 
with  nitre.  In  case  of  sulphides  and  arseniates  they  must 
first  be  roasted  on  charcoal. 

If  the  ore  contains  at  the  same  time  both  silica  and 
oxide  of  cobalt,  this  test  would  give  a  blue  colour  on  treat- 
ing it  in  this  way,  from  the  cobalt  present;  therefore 
the  test  for  manganese  is  destroyed  and  the  mineral  must 
be  determined  by  the  humid  way. 


PART  II.  TIN  AND  ANTIMONY.  55 

TIN. 

Heat  any  compound  supposed  to  contain  tin  with  a  flux 
made  of  equal  parts  of  borax  and  cyanide  of  potassium.  A 
malleable  globule  of  tin  will  be  obtained. 

Sulphides  of  tin  must  be  first  roasted  on  charcoal, 
then  treated  in  E.F.  with  soda  and  borax.  A  metallic 
button  of  tin  will  be  obtained,  which  can  always  be 
detected  by  removing  the  slag  from  it,  and  again  placing 
it  on  charcoal  and  applying  the  R.F.  The  globule  cannot 
be  kept  bright,  and  becomes  covered  with  a  crust  of  oxide, 
which  can  only  be  removed  with  difficulty  by  adding  borax. 
For  further  particulars  on  tin,  see  Tin  Assay. 

ANTIMONY. 

Antimony  fuses  easily  on  charcoal,  and  coats  the  char- 
coal in  R.F.  or  O.F.  with  oxide  of  antimony  (nearer  the 
assay  than  the  oxide  of  arsenic)  in  a  thin  layer  of  bluish 
white,  and  it  can  be  driven  about  the  charcoal  by  a  gentle 
O.F.  without  colouring  the  flame,  but  if  a  R.F.  be  used 
the  flame  will  be  coloured  a  faint  greenish  blue.  As  the 
sublimate  of  antimony  is  less  volatile  than  that  of  arsenic 
it  may  be  easily  distinguished  from  the  last. 

When  metallic  antimony  is  fused*  on  charcoal  and 
heated  to  redness,  and  the  blowing  stopped,  the  fused  metal 
keeps  itself  a  long  time  liquid  and  evolves  a  dense 
white  smoke,  which  deposits  on  the  charcoal  and  at 
last  coats  the  globule  itself  with  white  pearly  crystals 
of  oxide  of  antimony.  This  phenomenon  is  due  to  the 
absorption  of  oxygen  by  the  metal  and  the  heat  eliminated 
in  the  combination. 

Antimony  with  lead  and  bismuth  may  be  detected  by 
dissolving  the  above  metals  in  boracic  acid,  provided  the 


56  QUALITATIVE  DETERMINATION.  PART  II. 

fused  mass  is  kept  covered  with  the  blue  flame.  A 
coating  of  fine  oxide  of  antimony  is  formed,  if  the  heat 
is  not  applied  too  strong. 

Antimony  and  zinc  both  give  a  white  sublimate  on 
charcoal  near  the  assay.  The  zinc  oxide  is  not  volatilised 
in  the  outer  flame,  whilst  the  oxide  of  antimony  can  be 
driven  from  place  to  place  or  almost  entirely  volatilised. 
If  antimony  is  combined  with  tin  or  copper,  the  assay  is 
treated  on  charcoal  in  E.F.  with  soda  and  borax ;  by  this 
means  small  metallic  globules  are  formed.  The  globules 
are  separated  by  triturating  and  washing  in  the  horn  spoon. 
The  globules  are  then  fused  on  charcoal  in  the  R.F.  with 
3  to  5  times  their  volume  of  lead  and  a  little  boracic 
acid.  If  the  glass  only  is  exposed  to  the  E.F.  the 
antimony  is  volatilised,  and  it  coats  the  coal  distinctly 
with  its  oxide. 

In  alloys  of  copper,  silver,  lead,  and  iron,  a  small  piece 
of  the  alloy  should  be  dissolved  in  nitric  acid,  and  the 
antimony  will  be  found  in  an  insoluble  white  powder  (anti- 
monic  acid),  and  it  should  be  then  dried  and  treated  on 
charcoal  for  the  antimonial  sublimate. 


SILVER. 

Silver  can  be  detected  with  the  greatest  accuracy,  and 
the  percentage  estimated  by  following  the  instructions  in 
Silver  Assay. 

GOLD. 

Gold  can  be  detected  with  great  certainty,  and  the 
percentage  estimated,  by  following  the  rules  laid  out  in 
the  Gold  Assay. 


PART  II.  CHROMIUM  AND   IKOX.  5  7 

CHROMIUM. 

The  oxides  of  chromium  afford  a  distinct  reaction 
before  the  blowpipe  when  they  are  tested  in  the  O.F.  with 
borax  or  salt  of  phosphorus,  the  beads  appearing  yellowish 
green  when  quite  cool ;  and  the  bead  (if  free  from  the  oxides 
of  lead  or  copper)  in  the  R.F.  becomes  a  beautiful  eme- 
rald green.  If  the  above  metals  are  present  the  beads 
become  when  cool  opaque,  red,  or  grey. 


IRON. 

The  sesquioxide  of  iron  is  unchanged  by  the  O.F.,  but 
in  the  R.F.  it  loses  part  of  its  oxygen,  and  then  be- 
comes black  and  is  attracted  by  the  magnet. 

In  O.F.  it  dissolves  in  borax,  and  if  a  small  quantity 
is  present  the  glass  is,  whilst  hot,  yellow,  and,  when  cold, 
colourless.  If  in  a  larger  amount  it  is,  when  hot,  red, 
and,  when  cold,  yellow ;  and  if  fully  saturated  is,  when 
hot,  dark  red,  and,  on  cooling,  dark  yellow. 

In  R.F.  the  glass  formed  as  above  becomes  bottle 
green,  and  if  treated  on  charcoal  with  a  little  metallic 
tin  it  becomes  first  a  bottle -green  colour,  and  on  continued 
reducing  copperas  green. 

With  phosphate  salt  in  O.F.  the  glass  formed  is,  when 
hot,  yellowish  'red,  and,  in  the  course  of  cooling,  it  loses 
colour,  becoming  yellow,  then  greenish,  and  lastly  co- 
lourless when  cold.  When  saturated  it  is,  when  hot,  dark 
red,  and,  in  cooling,  successively  brown  red,  dirty  green, 
and  then  brownish  red  when  cold.  The  latter  colours 
show  themselves  much  quicker  during  cooling  than  when, 
borax  is  used. 

In  the  R.F.  the  phosphate  glass,  if  it  does  not  contain 
much  iron,  is  unchanged,  but  if  more  saturated  with  iron 


58  QUALITATIVE  DETERMINATION.  PART  II. 

it  becomes,  when  red  hot,  and,  in  cooling,  successively 
yellow,  greenish,  and  at  last  reddish  when  cold.  Treated 
with  glass  on  charcoal,  this  glass  becomes,  on  cooling,  green, 
and  when  cold  colourless. 

In  detecting  the  presence  of  iron  in  its  numerous 
compounds  the  reactions  of  borax  and  salt  of  phosphorus 
will  in  most  cases  be  sufficiently  characteristic. 

In  metallic  alloys  which  are  not  easily  fusible  it  is 
only  necessary  to  treat  them  with  borax  on  charcoal  in  an 
O.F.  until  the  glass  has  taken  up  sufficient  of  the  oxide 
formed  to  give  it  a  distinct  colour.  If  the  alloy  is  very 
fusible,  from  containing  lead,  tin,  bismuth,  antimony,  or 
zinc,  the  R.F.  should  be  used  by  directing  it  on  the 
glass,  which  causes  it  to  absorb  as  little  as  possible  of 
these  metals.  In  either  case  the  glass  is,  whilst  still  fused, 
separated  by  the  forceps  and  treated  on  clean  charcoal  with 
the  R.F.,  which  separates  the  readily  reducible  metals, 
especially  copper,  nickel,  arsenic,  bismuth,  antimony,  and 
zinc  (which  are  to  a  great  part  volatilised  and  sublimed  on 
the  charcoal  around),  and  leaves  the  glass  coloured  bottle 
green,  due  to  iron.  If  the  alloy  contained  tin  the  assay  may 
be  of  a  copperas  green  colour ;  if  not  it  becomes  so  by  treat- 
ing with  E.F.  on  charcoal  with  metallic  tin  (should,  how- 
ever cobalt  have  been  present  the  glass  will  turn  out  blue). 
The  bead  (free  from  any  adherent  reduced  metallic  matter) 
should  now  be  treated  on  platinum  wire  in  a  good  O.F. 
until  all  iron  is  fully  oxidised  (if  the  colour  is  too  in- 
tense for  inspection  a  part  of  it  only  need  to  be  taken 
and  fused  with  fresh  borax,  so  as  to  dilute  it),  when,  accord- 
ing to  the  proportion  of  iron  present,  the  colour  will  be  more 
or  less  yellow,  or  even  brown  red.  If  a  little  cobalt  is 
present  the  glass,  while  warm,  is  a  dark  green,  and  when 
cold  green  forms  the  admixture  of  colours.  When,  on  the 
contrary,  but  little  iron  is  present  along  with  much  cobalt 


PART  II,  IRON.  59 

it  will  appear,  when  hot,  green,  but  on  cooling  pure 
blue. 

Compounds  of  iron  with  arsenic  and  sulphur  may  be 
examined  by  several  methods. 

(a)  In  most  cases  it  is  best  to  fuse  the  substance 
with  borax  on  charcoal,  using  the  K.F.,  and  when  the 
whole  is  in  fusion  the  flame  should  be  directed  on  the 
glass  alone,  so  that  the  air  may  have  access  to  the  metallic 
globules.  As  soon  as  the  glass  begins  to  be  coloured  by  the 
absorbed  metallic  oxide  it  is  removed  by  the  forceps,  and 
can  be  examined  for  iron  in  both  flames  and  with  tin. 

(6)  The  sulphide  or  arsenide  may  be  calcined  on  charcoal, 
and  a  little  of  the  oxide  thus  produced  is  taken  up  by  a 
borate  globule  upon  platinum  wire  in  O.F.,  until  the  glass 
is  coloured.  Frequently  when  no  metals  having  strong  co^ 
louring  properties  are  present  this  test  suffices  at  once  to 
determine  the  presence  or  absence  of  iron.  If  not,  the 
glass  can  be  treated  on  charcoal  in  E.F.,  which  separates 
copper,  nickel,  or  any  other  easily  reducible  metals  (some- 
times to  effect  the  separation  of  such  metals  a  small 
piece  of  gold  or  silver  may  be  added  to  them,  as  it  en- 
ables the  metals  to  separate  much  quicker  by  so  alloying)  ; 
then  the  bead  is  left  with  the  iron  reactions  visible  and  it 
can  be  examined  as  before. 

(c)  According  to  Plattner  the  powdered  substance  can 
be  fused  with  borax  and  some  lead  on  charcoal,  covering 
the  whole  with  a  good  E.F.  When  the  borax  has  united 
and  formed  a  pearl  the  flame  is  directed  on  to  this  alone, 
so  that  air  has  access  to  the  fluid  metallic  globule. 

When  the  borate  is  coloured  by  the  absorbed  metallic 
oxides  it  should  be  removed  quickly  with  the  forceps,  and 
treated  on  fresh  charcoal  in  E.F.  to  reduce  any  oxide  of 
lead  in  the  glass,  after  which  it  may  be  examined  for  iron 
reactions  as  usual. 


60  QUALITATIVE   DETERMINATION.  PART  II. 

In  oxides,  when  no  copper,  nickel,  chromium,  or  uranium 
is  present,  the  iron  is  recognised  without  difficulty.  In 
case  of  uranium  a  humid  analysis  is  necessary,  as  this 
metal  gives  the  same  coloration  as  iron. 

With  nickel  the  colour  is  more  or  less  brownish  yellow 
or  yellowish  brown. 

In  case  of  both  nickel  and  copper  they  may  (as  before 
mentioned)  be  reduced  out  of  the  glass,  when  the  colour  of 
iron  is  then  distinctly  seen.  With  cobalt  the  colour  of  the 
glass  has  already  been  noted,  but  if  very  little  iron  is 
present  the  wet  way  must  be  used.  If  manganese  is 
present  the  colour  in  O.F.  will  be  violet  red,  or  if  very  much 
is  present  dark  red  when  hot,  and,  on  cooling,  red  with  a 
violet  tinge.  On  treating  such  a  glass  in  R.F.  on  charcoal 
with  tin  the  manganese  colour  disappears  and  the  copperas 
green  is  at  once  seen.  If  very  little  manganese  is  present 
merely  treat  it  in  R.F.,  which  will  be  sufficient  to  reduce 
the  manganese  and  bring  forward  the  bottle-green  colour 
due  to  iron. 

When  a  great  deal  of  manganese  is  present  the  phos- 
phate test  shows  the  iron  at  once,  as  the  manganese  colour 
of  this  glass  is  not  very  intense  in  the  O.F.,  and  in  E.F.  it 
becomes  colourless,  whilst  the  iron  colour  after  treatment 
with  K.F.  remains  generally  reddish. 

When  iron  is  in  combination  with  chromium  the  blow- 
pipe test  does  not  give  a  sufficiently  decided  result,  owing 
to  the  colours  produced  by  the  chromium., 

If,  however,  the  substance  be  melted  in  the  platinum 
spoon  with  3  parts  nitre  and  1  part  soda,  and  the  result 
washed  well  with  water,  the  residual  oxide  will  at  once 
react  for  iron  as  usual. 

If  tungsten  or  titanium  is  present  the  O.F.  will,  with 
borax  or  phosphorus  salt,  give  the  iron  reaction,  as  the 
above  metals  give  too  feeble  a  yellow  colour  to  interfere  with 


PART  II.  IRON   AND   COBALT.  61 

it,  also  with  borax  in  R.F.,  but  with  phosphate  in  R.F.  both 
of  these  become  darkened  to  brown  red.  The  compounds 
of  iron  with  carbonic  acid,  sulphuric  acid,  phosphoric 
acid,  arsenic  acid,  tantalic  acid,  silicic  acid,  and  alumina 
are  in  general  easily  shown  to  contain  iron  by  the  reactions 
with  borate  and  phosphate  salts.  It  is  also  the  case  with 
most  slags  and  other  products  of  the  arts. 

In  such  metallurgical  products  as  pig  iron,  steel, 
brass,  black  copper,  copper,  tin,  or  lead  (containing  iron), 
speiss,  regulus,  &c.,  the  iron  can  easily  be  showrn  by  the 
treatment  given  for  alloys  or  compounds  of  sulphur  and 
arsenic. 

COBALT. 

Before  the  blowpipe  in  O.F.  the  oxide  is  unchanged. 
In  R.F.  it  does  not  fuse,  shrinks  a  little,  and  is  reduced  to 
a  metallic  powder,  which  receives  lustre  by  friction  and  is 
attracted  by  the  magnet.  In  both  O.F.  and  R.F.  the  oxide 
is  dissolved  by  borax,  and  gives,  both  when  hot  and  cold,  a 
pure  blue  glass,  which  is  seen,  especially  on  cooling,  to  be 
less  intense  than  with  borax  glass,  from  equal  saturation. 

On  platinum  in  O.F.  with  soda  the  oxide,  if  in  very 
small  quantity,  dissolves  to  a  clear  bright  red  mass,  which 
becomes  grey  on  cooling.  The  examination  for  cobalt  is 
generally  easy,  and  especially  so  when  no  other  strongly 
colouring  metal  is  present.  This  being  the  case,  the  sub- 
stance, when  treated  with  borax  in  O.F.,  will  indicate  the 
presence  of  cobalt  by  the  blue  colour  of  the  glass.  If  iron 
is  present  the  glass,  when  warm,  may  appear  green,  from 
the  admixture  of  colours,  but  on  cooling  (if  the  iron  be  not 
in  very  large  amount)  the  blue  is  seen  above  the  peculiar 
colour  arising  from  the  mixture  of  bottle  green  and  blue. 
When  the  glass  is  treated  in  the  R.F.  it  is  not  easily  mis- 
taken for  any  other  reaction ;  also  the  action  of  the  R.F. 


62  QUALITATIVE   DETEBMINATICXN7.  PART  II. 

renders  a  manganese  glass  colourless.  This  substance 
if  present,  is  no  obstacle  in  the  way  of  recognising  the 
blue  of  the  cobalt,  as  it  is  when  using  the  O.F.  with  iron 
and  cobalt. 

Plattner  detects  cobalt  in  metallic  alloys  of  nickel  by 
converting  the  metal  into  an  arsenide  before  testing  it  for 
cobalt  by  mixing  it  in  thin  scales  or  filings  with  a  little 
metallic  arsenic,  fusing  them  together  in  a  small  cavity  on 
charcoal  with  the  R.F.,  and  treating  the  fused  button  a 
short  time  with  borax  directly  with  the  tip  of  the  blue 
flame  ;  if  any  cobalt  is  present  the  glass  becomes  blue,  and 
if  the  amount  is  not  too  small  the  cleansed  button  will 
impart  a  blue  colour  to  a  fresh  portion  of  borax  also. 

NICKEL. 

The  protoxide  in  the  O.F.  is  unchanged.  In  the  R.F. 
it  is  reduced  to  an  infusible  metallic  powder,  which  is 
magnetic. 

With  borax  in  the  O.F.  on  platinum  wire  a  little  of  the 
oxide  colours  the  hot  glass  violet,  but  when  cold  a  pale 
reddish  brown ;  with  more  oxide  the  colours  are  darker.  In 
R.F.  with  borax  the  glass  becomes  grey  and  cloudy  or 
quite  opaque,  owing  to  finely  divided  metallic  nickel.  On 
continuing  the  blast  the  reduced  metallic  particles  collect 
together  without  fusing,  and  the  glass  becomes  colourless. 

With  phosphate  salt  on  platinum  wire  in  O.F.  it 
dissolves  to  a  reddish  glass,  yellow  on  cooling.  In  R.F.  on 
platinum  wire  it  is  unchanged.  On  charcoal  with  tin  it 
becomes  at  first  opaque  and  grey,  but  after  long  blowing  all 
the  nickel  is  reduced  and  the  glass  becomes  colourless. 

With  soda  it  is  insoluble  in  O.F.,  but  in  R.F.  on  char- 
coal it  is  easily  reduced  to  white  metallic  particles,  which, 
after  washing,  follow  the  magnet. 


PART  II.  NICKEL    AND  ZINC.  63 

Plattner  detects  a  small  quantity  of  nickel  in  oxides  of 
cobalt, manganese,  and  iron  by  dissolving  a  small  quantity  in 
borax  on  platinum  wire  in  O.F. — the  dark  or  opaque  bead  is 
shaken  off,  and  two  or  three  such  beads  prepared.  These 
are  treated  in  a  cavity  on  coal,,  or  in  a  coal  crucible,  with 
a  small  pure  gold  button  in  a  strong,  active  K.F.  until  it 
is  certain  that  all  the  nickel  is  reduced  from  the  bead  and 
collected  in  the  gold  button,  which  has  been  brought  into 
contact  with  every  portion  of  the  fluid  glass  by  carefully 
turning  the  coal.  When  the  button  has  solidified,  it  is 
lifted  from  the  glass  and  freed  from  any  adherent  glass 
between  paper  on  the  anvil.  If  the  borax  glass  was  not 
supersaturated  with  oxides,  so  that  none  of  the  cobalt  could 
be  reduced,  the  gold  button  treated  for  some  time  in  the  O.F. 
on  coal  with  phosphate  will  impart  to  this  only  the  nickel 
colour,  reddish  to  brownish  red  whilst  hot,  and  yellow  to  red- 
dish yellow  after  cooling,  according  to  the  amount  dissolved. 
If,  however,  cobalt  has  been  reduced  it  will  oxidise  sooner 
than  the  nickel,  and  either  produce  a  blue  cobalt  bead  or 
a  bead  which  will  be  dark  violet  when  hot  and  dirty  green 
on  cooling,  if  some  nickel  had  been  oxidised. 

In  either  case  the  button,  freed  from  glass,  is  treated 
with  fresh  phosphate  in  O.F.  until  the  hot  glass  seems 
coloured,  when,  if  the  original  borax  beads  had  not  been  too 
highly  supersaturated,  the  glass  will  show  only  the  nickel 
coloration ;  if  the  metallic  oxides  were,  however,  free  from 
nickel  the  glass  will  be  colourless  (Plattner's  'Manual,' 
p.  245). 

ZINC. 

If  the  substance  contains  much  zinc,  or  when  it  is  free 
from  other  metals  which  form  a  sublimate  on  charcoal,  the 
presence  of  this  metal  is  easily  detected.  When  a  small 
amount  of  zinc  is  combined  with  much  lead,  bismuth,  or 


64  QUALITATIVE  DETERMINATION.  PART  II. 

antimony  it  is  quite  impossible  to  prove  its  presence  with 
certainty,  and  frequently  the  presence  of  tin  prevents  its 
detection. 

The  examination  for  zinc  is  in  all  cases  based  upon  the 
reduction  of  the  metal  or  the  formation  of  sublimate 
(white  when  cold  and  yellow  when  hot)  on  the  charcoal. 
This  sublimate,  being  further  tested  by  reheating  with  a 
solution  of  nitrate  of  cobalt,  produces  the  characteristic 
yellowish  green  colour. 

Large  quantities  of  oxide  of  lead  or  bismuth  in  the 
sublimate  may  obscure  this  reaction ;  but  in  some  cases 
the  lead  and  bismuth  oxides  may  be  driven  farther  off,  so 
as  to  leave  the  zinc  reaction  tolerably  clear. 

If  the  quantity  of  zinc  present  is  extremely  small, 
and  only  produces  a  very  faint  coating  of  sublimate,  which 
might  be  easily  lost  mechanically,  it  is  in  such  cases 
better  to  moisten  the  charcoal  first  with  a  drop  of  nitrate  of 
cobalt  before  blowing.  It  must,  however,  be  observed,  if 
much  antimony  or  tin  is  present,  a  greenish  colour  is  also 
produced  with  nitrate  of  cobalt  from  combinations  with 
the  oxide  of  cobalt  which  are  not  volatile  in  the  O.F.  (the 
colour  with  tin  a  bluish  green),  and  in  such  cases  dependence 
cannot  be  placed  on  this  reaction. 

When  much  zinc  is  present  a  zinc  flame  is  observed 
in  K.F.,  and  the  charcoal  is  covered  with  a  strong  sublimate, 
closer  to  the  assay  than  that  of  lead  oxide.  Substances 
containing  zinc  in  combination  with  sulphur  can  be  treated 
alone  on  charcoal  in  K.F. 

Those  containing  zinc  as  oxide  with  but  little  sulphur 
are  treated  with  soda  on  charcoal  in  the  E.F. 

Those  containing  other  metallic  oxides  and  earths 
require  borax  in  addition.  A  mixture  of  2  parts  soda  with 
1  to  1 1  borax  glass  on  charcoal  in  E.F.  (especially  when 
in  combination  with  alumina)  soon  frees  the  zinc,  and  the 
usual  sublimate  is  readily  formed. 


PART  II.  CADMIUM.  65 

CADMIUM. 

Metallic  cadmium  fuses  readily  and  volatilises,  covering 
the  charcoal  with  a  reddish  brown  (in  thin  films),  dark 
yellow,  or  orange-coloured  sublimate  of  the  oxide,  which 
still  farther  off  on  the  charcoal  gives  an  iridescent  play  of 
colours. 

The  oxide  treated  on  platinum  is  unchanged  in  O.F. 
On  charcoal  in  K.F.  it  is  reduced,  and  covers  the  charcoal 
with  a  red  brown  to  dark  yellow  sublimate  (colour  best 
seen  when  cold),  as  in  the  case  of  metallic  cadmium. 

In  borax  glass  in  O.F.  the  oxide  readily  dissolves, 
and  gives  a  transparent  yellow  glass  when  hot ;  on  cool- 
ing it  is  almost  colourless  ;  on  larger  saturation  the  glass 
can  be  flamed  to  a  milky  enamel,  and  when  still  more 
saturated  it  becomes  enamel  white  on  cooling. 

On  charcoal  in  K.F.  che  phosphatic  glass  is  slowly  and 
but  partially  reduced,  giving  but  a  very  faint  sublimate 
of  a  dark  yellow  colour  ;  the  true  colour  is  only  seen  well 
on  cooling.  An  addition  of  tin  hastens  the  reduction. 

With  soda  in  O.F.  the  oxide  remains  unchanged,  but 
in  K.F.  it  is  reduced,  with  the  production  of  the  charac- 
teristic sublimates  before  described. 

It  does  not  give  any  characteristic  reaction  with 
nitrate  of  cobalt. 

In  searching  for  this  mineral  the  means  of  detecting 
the  cadmium  depends  entirely  upon  the  reduction  and  the 
subsequent  volatilisation  of  the  metal,  giving  rise  to  the 
characteristic  sublimate  of  the  metal. 

Substances  containing  much  cadmium  give  the  above 
reaction  if  powdered  finely  and  heated  quickly  in  the  K.F. 

If  the  mineral  contains  as  little  as  1  per  cent,  of  cadmium 
it  is  better  to  mix  the  powder  with  soda  and  heat  for  a  very 
short  time  in  a  K.F.,  when  the  sublimate  will  be  seen. 

F 


66  QUALITATIVE  DETERMINATION.  PART  II. 

As  zinc  is  frequently  present  with  cadmium,  the  heat,  if 
continued  too  long,  will  also  drive  off  the  less  volatile  zinc, 
the  white  sublimate  of  which  may  more  or  less  obscure 
the  cadmium  reaction. 

COPPER. 

The  oxides  of  copper,  when  heated  on  charcoal  in  K.F. 
with  soda,  yield  a  metallic  button  of  copper. 

When  heated  in  the  O.F.  on  platinum  wire  with  borax, 
they  colour  the  glass  strongly  ;  a  little  oxide  causes  a  green 
glass  when  hot  and  a  blue  when  cold,  and  with  more  it  is  dark 
green  to  opaque  when  hot,  but  greenish  blue  on  cooling. 

With  borax  in  the  K.F.  on  platinum  wire,  if  saturated 
to  a  certain  degree,  the  glass  soon  becomes  colourless,  but 
on  cooling  it  becomes  red  and  opaque.  On  charcoal  the 
copper  is  reduced  to  metal,  and  the  cold  glass  is  quite 
colourless. 

The  sulphides  of  copper  are  roasted  on  charcoal  with 
the  O.F.  and  E.F.  alternately,  and  on  the  completion  of 
the  roasting  soda  is  added,  a  E.F.  applied,  and  a  globule 
of  metallic  copper  produced. 

Silicates  and  other  salts  of  copper  dissolve  in  O.F.  in 
the  glass  fluxes  to  green  beads,  which  should  be  blue  on 
cooling. 

For  full  details  of  copper  assay  see  p.  146. 

LEAD. 

Metallic  lead  fuses  easily,  tinging  the  flame  light  blue, 
and  in  both  K.F.  and  O.F.  volatilises,  covering  the  char- 
coal around  it  with  a  sublimate  of  pure  oxide  of  lead, 
dark  orange  yellow  when  hot  and  sulphur  yellow  when 
cold,  on  the  outskirts  of  which  is  generally  seen  a  thin 
bluish-white  sublimate  of  carbonate  of  lead.  The  flame 


PART  II.  LEAD.  67 

of  the  blowpipe  chases  these  sublimates  from  place  to 
place  on  the  charcoal,  which,  when  red  hot,  reduces  the 
oxides,  volatilising  the  metal  to  a  greater  distance  when  it 
is  redeposited  as  a  sublimate  of  oxide,  at  the  same  time 
colouring  the  flame  light  blue. 

The  protoxide  of  lead  heated  in  O.F.  on  platinum  alone 
becomes  darker  in  colour  and  fuses  to  a  yellow  glass.  The 
red  oxide  becomes  almost  black,  and  at  a  low  red  heat  is 
converted  into  protoxide,  and  it  behaves  as  before  stated 
under  similar  circumstances. 

On  charcoal  in  both  O.F.  and  E.F.  all  the  oxides  are 
reduced  to  metallic  lead  with  effervescence,  which  on  con- 
tinued blowing  is  volatile  and  is  deposited  as  a  sublimate 
of  oxide,  which  can  be  reduced  again  to  metallic  lead  by 
the  K.F.,  which  is  thus  tinged  light  blue. 

With  borax  glass  in  O.F.  the  oxides  dissolve  readily, 
forming  a  clear  yellow  glass,  colourless  on  cooling.  With 
greater  saturation  this  glass  can  be  flamed  opaque,  and 
upon  full  saturation  on  cooling  it  becomes  of  itself  a 
yellow  opaque  enamel. 

In  R.F.  this  borax  globule  upon  charcoal  spreads  out 
with  effervescence,  and  the  lead  may  be  reduced  to  its 
metallic  state  by  continued  blowing,  leaving  a  clear  borax 
globule. 

With  phosphate  salt  in  O.F.  the  oxide  (the  same  as 
with  the  borate)  requires  more  saturation  before  the 
globule  shows  any  yellow  colour  when  hot. 

In  R.F.  the  phosphate  salt  globule  on  charcoal  becomes 
greyish  and  opaque,  and  when  the  globule  is  saturated  the 
charcoal  around  is  covered  by  a  yellow  sublimate  of  oxide. 
The  addition  of  tin  to  the  globule  makes  it  more  opaque  and 
darker  grey  in  colour,  but  it  never  becomes  quite  opaque. 

With  soda  on  platinum  wire  it  dissolves  in  O.F.  to  a 
clear  glass,  becoming  yellowish  and  opaque  on  cooling. 


o8  QUALITATIVE  DETERMINATION.  PART  II. 

With  soda  on  charcoal  it  is  reduced  to  metallic  lead  in 
E.F.,  which  on  continued  blowing  covers  the  charcoal  with 
oxide. 

INDIUM. 

In  O.F.  the  oxide  becomes  of  a  dark  yellow  colour, 
does  not  fuse,  and  on  cooling  recovers  its  lighter  colour. 

On  charcoal  in  E.F.  it  is  slowly  reduced  and  volatilised, 
and  the  oxide  sublimed  on  to  the  charcoal.  During  the 
reduction  the  outer  flame  is  coloured  very  distinctly  violet. 
With  borax  in  O.F.  it  dissolves  to  a  clear  glass,  feebly 
yellowish  whilst  hot,  but  colourless  on  cooling.  A  more 
saturated  globule  becomes  opaque. 

With  borax  in  R.F.  the  glass  does  not  change,  but  on 
charcoal  it  commences  to  reduce  and  to  give  a  sublimate 
on  the  charcoal ;  at  the  same  time  the  violet  colouring 
of  the  outer  flame  is  seen,  and  is  not  concealed  by  the  soda 
coloration. 

With  phosphate  salt  the  reactions  are  the  same  as  with 
borate,  but  if  tin  be  added  to  the  glass  in  the  R.F.  the 
glass  on  cooling  becomes  grey  and  opaque. 

With  soda  in  O.F.  it  is  not  dissolved,  but  on  charcoal 
in  R.F.  is  reduced,  and  part  of  the  metal  volatilises  and 
forms  a  sublimate  of  oxide  on  the  charcoal,  whilst  some 
nearly  silver  white  globules  of  indium  are  seen  in  the 
soda. 

BISMUTH. 

Bismuth  fuses  very  easily,  and  gives  a  coat  of  oxide, 
which  is  dark  orange  yellow  when  hot,  and  lemon  yellow 
when  cold,  being  yellowish  white  in  thin  layers. 

The  yellow  coat  is  pure  oxide,  and  the  yellowish  white 
one  (which  is  at  the  greatest  distance)  is  carbonate  with 


PART  II.  BISMUTH   AND  TITANIUM.  69 

some  oxide  of  bismuth.  It  can  be  driven  about  on  the 
glowing  coal  like  lead,  but  does  not  colour  the  R.F.  during 
the  operation. 

Bismuth  combined  with  sulphur  gives  on  charcoal  a 
white  coat  of  sulphate  of  bismuth  beyond  the  yellow  coat, 
but  it  is  prevented  by  a  small  addition  of  soda. 

When  much  lead  or  antimony  is  present,  roast  care- 
fully on  charcoal,  then  fuse  with  3  times  its  volume 
of  bisulphate  of  potash  in  the  platinum  spoon,  then  treat 
the  mass  with  water  in  a  small  porcelain  dish  until  every- 
thing is  detached  from  the  spoon.  Sulphate  of  potash 
and  other  soluble  sulphates  are  dissolved,  leaving  neutral 
sulphate  of  lead  and  basic  sulphate  of  bismuth.  Antimony, 
if  present,  remains  behind  as  acid. 

After  decanting  the  clear  solution  the  residue  is  boiled 
in  distilled  water,  to  wThich  a  few  drops  of  sulphuric  acid  and 
some  nitric  acid  are  added,  when  the  sulphate  of  bismuth 
dissolves,  leaving  a  residue  of  sulphate  of  lead  with  any 
oxide  of  antimony  present.  After  nitration  the  bismuth 
is  thrown  down  from  the  warm  nitrate  by  means  of  salt 
of  phosphorus  as  a  white  precipitate,  which  is  collected 
on  a  filter  and  tested  with  phosphate  salt. 

The  phosphate  bead  on  platinum  wire  is  colourless,  or 
faintly  yellow,  but  on  coal  with  tin  in  E.F.  becomes  dark 
grey  on  cooling,  behaving  there  like  oxide  of  bismuth. 

Oxides  of  bismuth,  if  treated  either  alone  or  with  soda 
on  charcoal,  give  the  usual  bismuth  coating. 

TITANIUM. 

Titanic  acid  both  in  E.F.  and  O.F.  on  charcoal 
assumes  a  yellow  colour,  but  it  is  white  again  on  cooling. 

With  borax  on  platinum  wire  in  O.F.  it  dissolves 
easily  to  a  clear  glass ;  if  much  is  present  it  appears 


70  QUALITATIVE  DETERMINATION.  PART  II. 

yellow  whilst  hot  and  colourless  on  cooling,  and  becomes 
opaque  by  flaming.  In  R.F.  a  small  addition  yields  a 
yellow  glass ;  more  oxide  yields  a  dark  yellow  to  brown 
glass.  A  saturated  glass  becomes  emanel  blue  by  flaming. 

With  phosphate  salt  on  platinum  wire  in  O.F.  it  dis- 
solves easily  to  a  clear  glass,  yellow  while  hot.  In  R.F. 
the  glass  becomes  yellow  while  hot,  but  reddens  on  cool- 
ing and  assumes  a  fine  violet  colour.  If  the  acid  contains 
iron  the  glass  becomes  brownish  yellow  to  brownish  red  on 
cooling. 

With  soda  in  O.F.  on  charcoal  it  dissolves  with  effer- 
vescence to  a  dark  yellow  glass,  which  crystallises  on  cool- 
ing a,nd  thereby  evolves  so  much  heat  that  the  globule 
glows  strongly  again.  When  perfectly  cold  the  glass  is 
greyish  white  to  white. 

With  cobalt  solution  in  the  O.F.  it  assumes  a  yellowish 
green  colour,  similar  to  oxide  of  zinc,  but  not  so  fine. 

Plattner  recommends  the  following  plan  to  detect 
small  amounts  of  titanium  : — In  complex  substances  which 
give  no  decisive  reaction  for  titanium  with  the  fluxes  the 
finely  powdered  substance  is  fused  in  a  platinum  spoon  at 
a  moderate  red  heat  with  6  to  8  times  its  weight  of 
bisulphate  of  potash,  the  mixture  being  melted  in  small 
portions  at  a  time.  The  mass  is  then  dissolved  in  just 
sufficient  water  in  a  porcelain  dish  over  the  lamp,  and  the 
insoluble  parts  allowed  to  settle. 

The  solution,  if  concentrated,  may  be  heated  to  boiling. 
The  clear  solution  is  then  poured  into  a  larger  dish,  mixed 
with  a  few  drops  of  nitric  acid  diluted  with  at  least  6 
times  as  much  water,  and  then  boiled. 

If  the  substance  contains  titanium  the  latter  is  dis- 
solved by  the  fusion  with  bisulphate  of  potash  and  treat- 
ment with  water,  and  it  is  precipitated  from  the  acid 
solution  by  continued  boiling  as  white  titanic  acid. 


PART  II.        TITANIUM,  MEECUEY,  AND   PLATINUM.  71 

If  the  solution  is  not  acidified  with  nitric  acid  before 
boiling,  a  yellow  ferruginous  titanic  acid  is  obtained  when 
the  substance  contains  iron.  The  precipitated  titanic  acid 
is  collected  upon  a  small  filter,  washed  with  water  con- 
taining nitric  acid,  and  tested  with  phosphate  salt  either 
on  platinum  wire  or  charcoal. 

If  the  amount  of  titanic  acid  is  so  small  that  in  R.F. 
it  does  not  impart  to  the  phosphate  salt  the  violet  colour 
of  the  sesquioxide  of  titanium,  add  a  little  sesquioxide 
of  iron  when  the  assay  is  upon  a  wire,  or  a  small  piece  of 
iron  wire  when  on  charcoal,  and  fuse  the  glass  a  short 
time  with  the  R.F. ;  it  then  appears  yellowish  while  hot 
and  brownish  red  when  cool  ('  Manual,'  1873,  p.  323). 

MERCURY. 

The  assay  for  mercury  is  treated  fully  on  p.  135. 

PLATINUM. 

Platinum,  when  treated  with  borax  or  phosphate  salt, 
does  not  fuse,  and  is  neither  oxidised  nor  dissolved. 

Platinum  is  found  native,  and  forms  alloys  with 
other  metals — iron,  copper,  rhodium,  iridium,  ruthenium, 
osmium,  gold,  and  silver.  To  examine  an  alloy  for  plati- 
num dissolve  a  small  piece  in  aqua  regia  (3  parts  hydro- 
chloric acid  and  1  part  nitric  acid).  If  there  is  any  black, 
fine,  metallic  insoluble  powder  in  the  bottom  of  the  flask 
it  is  iridium.  Separate  it  by  decanting  carefully,  then 
evaporate  the  blood-red  solution  almost  to  dryness ;  the 
acid  fluid  is  then  diluted  with  water ;  a  few  drops  of  a 
solution  of  potassa  is  added.  A  yellow  precipitate  is 
formed,  which  consists  chiefly  of  platinchloride  of  potas- 
sium. 


72  QUALITATiV^  DETERMINATION.  PART  II. 


LITHIUM. 

Lithia,  when  heated  in  the  point  of  the  blue  flame, 
communicates  a  fine  purple-red  colour  to  the  outer  flame. 
According  to  Plattner,  when  lithia  is  fused  upon  platinum 
foil  it  causes  the  platinum  in  contact  with  it  to  acquire  a 
yellow  tarnish,  which  is  removed  by  water,  but  upon  drying 
or  heating  leaves  the  platinum  surface  without  lustre,  as 
if  acted  upon. 

To  detect  lithia  in  its  compounds  it  is  only  necessary 
to  heat  them  on  a  platinum  wire  or  in  the  platinum  forceps 
and  in  the  point  of  the  blue  flame.  Observe  the  purple-red 
colour  communicated  to  the  outer  flame.  This  reaction 
serves  also  for  silicates.  Those  which  contain  very  little 
lithia  require  to  be  tested  according  to  Turner's  method,  by 
mixing  I  part  of  the  impalpable  powder  with  2  parts  fluor 
spar  and  three  parts  bisulphate  of  potash,  and  by  addition  of 
a  little  water  rendering  the  mixture  plastic  enough  to  stick 
to  the  loop  of  a  platinum  wire.  This  is  now  subjected  to 
the  blue  flame.  If  no  lithia  is  present,  only  the  violet 
colour  due  to  the  potash  employed  will  be  seen,  but  if  the 
contrary  is  the  case  the  lithia  red  will  be  seen  even  more 
or  less  overpowering  the  violet.  The  presence  of  soda  in 
the  mineral  may  render  this  reaction  indistinct ;  but  if 
boracic  acid  is  contained  in  the  substance  the  green  colour 
due  to  this  body  will  be  first  seen,  but  it  subsequently 
gives  place  to  the  lithia  reaction.  In  testing  for  lithia  it 
must  be  remembered  that  strontia  and  lime  also  produce 
a  red  coloration  of  the  flame.  When  soda  is  present  along 
with  lithia  the  red  coloration  may  be  overpowered  by  the 
intense  soda  yellow,  especially  if  the  heat  employed  be 
high.  By  employing  the  outer  flame  and  less  heat  the 
lithia  reaction  is  frequently  seen  when  otherwise  invisible. 
Stein  states  that  1  part  lithia  in  2,580  parts  soda  gives 


PART  II.  LITHIUM,   OXYGEN,   AND   HYDROGEN.  73 

a  red  coloration,  if  the  substance  be  heated  so  as  to  soften 
and  render  it  porous  by  quenching  it  in  tallow  and  then 
heating  it  in  the  flame  of  a  candle. 

Potash  interferes  less  with  the  lithia  reaction,  but 
communicates  a  stronger  or  weaker  violet  tinge  in  propor- 
tion to  the  amount  present.  When  both  potash  and  soda 
are  associated  with  an  excess  of  lithia  the  outer  flame  will 
be  reddish  violet  nearest  and  reddish  yellow  farther  away 
from  the  assay.  If  soda  is  present  in  excess  both  potash 
and  lithia  reactions  disappear,  but  sometimes  the  lithia 
can  be  observed  by  using  less  heat,  as  before  men- 
tioned. 

If  a  lithia  mineral  containing  phosphoric  acid  (but  no 
soda)  be  treated  in  the  blue  flame,  two  distinct  colours  are 
seen  in  the  outer  flame,  which  do  not  mix  with  one  an- 
other, being  the  lithia  red  and  a  bluish  green  due  to  phos- 
phoric acid. 

OXY  GEN. 

According  to  Fuchs,  this  element  is  only  detected  in 
substances  which  can  readily  be  made  to  part  with  it  in  a 
free  state.  In  substances  that  give  up  their  oxygen  when 
heated  in  a  glass  tube,  the  gas  is  recognised  by  its  rekind- 
ling a  glowing  match.  This  reaction  is  often  inconclusive, 
owing  to  the  small  size  of  the  fragment  under  examination. 
However,  another  test  presents  itself  at  once  for  these 
small  quantities.  The  assay  is  heated  in  a  test  tube  with 
a  fragment  of  chloride  of  sodium  and  a  few  drops  of 
sulphuric  acid.  Chlorine  is  now  evolved  in  place  of  oxygen, 
and  it  may  be  recognised  by  its  characteristic  odour,  or  by 
its  bleaching  effect  on  a  piece  of  moist  litmus  paper. 

HYDROGEN. 

To  detect  hydrogen  in  water,  place  a  small  piece  of 
metallic  zinc  in  a  small  porcelain  cup,  and  add  a  few  drops 


74  QUALITATIVE  DETERMINATION.  PART  II. 

of  sulphuric  acid.     Hydrogen  gas  is  given  off,  which  is 
easily  recognised  by  its  sickly  odour. 

The  examination  for  hydrogen  does  not  come  within 
the  scope  of  a  blowpipe  investigation,  and  it  must  be  de- 
termined by  chemical  analysis. 

NITROGEN. 

Substances  containing  nitrates  detonate  when  heated 
on  charcoal.  Heated  in  a  tube  with  a  little  sulphuric 
acid,  they  give  off  red  fumes  of  nitric  peroxide.  A  small 
amount  of  a  nitrate  present  in  another  salt  or  substance 
can  be  readily  detected  by  heating  it  with  rather  more 
than  its  volume  of  bisulphate  of  potassa  in  a  closed  tube 
or  matrass.  The  tube  becomes  filled  with  gaseous  nitrous 
acid,  the  yellow  colour  of  which  may  be  seen  by  looking 
down  through  the  tube.  Should  there  be  so  little  nitrate 
present  that  this  colour  cannot  be  plainly  seen, the  minutest 
quantities  may,  according  to  Stein,  be  detected  by  heating 
the  assay  with  litharge,  which  at  first  absorbs  the  nitric 
acid,  but  yields  it  up  at  a  higher  temperature.  A  slip  of 
paper  which  has  been  immersed  in  a  solution  of  protosul- 
phate  of  iron,  free  from  sesquioxide  and  acidulated  with 
some  sulphuric  acid,  is  inserted  into  the  neck  of  the  tube, 
and  if  nitrous  acid  is  present  it  will  assume  a  yellowish  to 
brown  colour.  In  this  way  the  nitric  acid  in  a  mixture  of 
1  part  of  nitre  with  1,000  parts  of  sulphate  of  soda  con- 
taining only  0-0005  nitric  acid  can  be  distinctly  shown. 
The  paper  quickly  loses  its  colour  if  too  strongly  heated, 
and  therefore  the  tube  or  matrass  should  be  rather  long. 
Nitre,  soda  nitre,  and  nitrocalcite  are  immediately  re- 
cognised as  nitrates  by  the  above  tests,  and  their  bases 
may  be  distinguished  by  the  colour  they  impart  to  the 
flame. 


PART  II.  FLUORINE  AND   CHLORINE.  75 

FLUORINE. 

Fluorides,  when  treated  in  a  closed  tube,  give  off  fumes 
of  hydrofluoric  acid,  which  react  acid  with  test  papers  and 
sometimes  etch  the  glass.  If  no  acid  reaction  has  taken 
place,  first  heat  with  a  little  sulphuric  acid  in  the  closed  tube, 
and  if  that  still  does  not  evolve  fumes  of  hydrofluoric  acid 
heat  in  a  closed  tube  with  a  small  quantity  of  bisulphate 
of  potash.  In  case  no  characteristic  reaction  has  taken 
place  Berzelius  recommends  the  following  test : — 

The  finely  powdered  substance  is  mixed  with  phos- 
phate salt  (previously  fused  on  charcoal),  and  the  mixture 
heated  in  the  open  tube,  so  that  the  flame  can  be 
carried  inside  the  tube  by  the  current  of  air.  Under  the 
solvent  action  of  the  phosphate  upon  minerals  free  from 
silica,  hydrofluoric  acid  is  formed,  which  passes  through 
the  tube ;  and  it  can  be  recognised  both  by  its  peculiar 
pungent  odour  and  by  its  effects  on  the  glass,  which  it- 
attacks  and  renders  dull,  especially  where  any  moisture 
has  collected.  The  escaping  air  will  also  turn  Brazil-wood 
paper  yellow. 

CHLORINE. 

According  to  Berzelius, '  chlorine  may  be  detected  in  its 
compounds  by  dissolving  oxide  of  copper  in  salt  of  phos- 
phorus or  platinum  wire  in  O.F.  until  the  glass  is  opaque, 
and  then  causing  the  substance  under  examination  to 
adhere  to  the  soft  bead,  which  is  then  treated  with  the  tip 
of  the  blue  flame.' 

4  If  chlorine  is  present  the  bead  will  be  surrounded  with 
an  intense  azure  blue  flame  of  chloride  of  copper,  which 
volatilises  as  long  as  chlorine  remains.  A  fresh  addition 
of  the  substance  will  reproduce  this  reaction.  Bromine  is 
the  only  other  body  occuring  in  minerals  which  produces 


76  QUALITATIVE  DETERMINATION.  PART  II. 

a  similar  flame.'     As  the  above  frequently  occur  together 
the  result  is  not  satisfactory  without  a  still  further  in- 
vestigation.    When  a  substance  gives  the  azure  blue  re- 
action in  salt  of  phosphorus,  fuse  another  portion  of  the 
compound  in  phosphate  glass  with  copper  oxide.     As  soon 
as  the  fusion  is  complete  stop  blowing,  let  the  glass  cool, 
then  crush  into  the  finest  powder  on  the  agate  mortar 
and  attack  it  in  a  tube  or  matrass  with  a  small  quantity 
of  nitric  acid.     Add  water,  allow  the  assay  to  settle  for  a 
few  moments,  then  add  a  solution  of  nitrate  of  silver.     If 
chlorine  alone  is  present  the  precipitate  will  be  a  milky 
white.    If  the  compound  contains  as  much  as  J  per  cent,  of 
bromine  the  precipitate  will  have  a  beautiful  light  lemon 
yellow   tinge.     If  the   compound  contains   a   large  per- 
centage of  chlorine  to  a  very  small  percentage  of  bromine 
the  colour  will  only  be  observed  at  the  moment  of  precipita- 
tion ;  but  if  a  large  amount  of  bromine  is  in  the  compound 
the  yellow  colour  is  permanent,  and  will  of  ten  be  seen  en- 
tirely  separate    from  the   pure   milky  white  precipitate 
which  is  thrown  down  by  chlorine.     The  colours,  however, 
cannot  be  correctly  discerned  after  the  test  tube  has  been 
shaken  up.     In   mineral   waters  and  aqueous    salts   the 
slightest  traces  of  chlorine  can  be  detected  (if  very  dilute, 
evaporate  down)  by  adding  a  few  drops  of  nitrate  of  silver. 
A  milky  cloud   will  be    observed  immediately  after  the 
above  addition  if  any  chlorine  is  present. 

BROMINE. 

Bromides  behave  in  a  similar  manner  to  chlorine,  and 
with  phosphorus  salt  and  oxide  of  copper  the  same  reaction 
takes  place  as  with  silver.  The  flame,  however,  has  not  a 
pure  azure  blue  colour,  but  inclines  to  green,  especially  at 
the  edges. 


PART  II.  BROMINE,   IODINE,   AND   SULPHUR.  77 

When  all  the  bromine  has  been  eliminated  the  green 
flame  of  the  oxide  of  copper  alone  remains. 

To  distinguish  bromides  from  chlorides  Berzelius  has 
proposed  to  fuse  them  in  a  matrass  with  bisulphate  of 
potash,  when  bromine  and  sulphurous  acid  are  liberated, 
and  the  matrass  is  filled  with  reddish  yellow  vapours  of 
bromine,  which  can  be  recognised  by  their  similarity  to 
that  of  chlorine  notwithstanding  the  sulphurous  acid. 
Bromide  of  silver  forms  an  exception,  as  it  yields  very 
little  bromine,  but  it  may  be  distinguished  from  chloride 
of  silver  by  the  asparagus  green  colour  which  it  assumes 
when  exposed  to  the  sunlight  after  fusion  with  the  bi- 
sulphate of  potash. 

IODINE. 

Iodides,  if  fused  with  oxide  of  copper  in  a  phosphate 
bead,  produce  an  intense  green  flame. 

When  iodides  are  fused  in  the  matrass  with  bisul- 
phate of  potash,  the  iodine  is  sublimed  and  partly  fills 
the  matrass  with  violet  vapours,  while  sulphurous  acid  is 
simultaneously  evolved. 

The  test  is  so  delicate  that  small  quantities  of  iodine 
may  be  detected  in  salts,  &c. 

SULPHUR. 

Sulphur  fuses  in  the  matrass ;  sublimes,  leaving  a  fine 
yellow  sublimate  when  cool.  If  ignited  on  charcoal  it 
burns  with  a  bluish  flame,  evolving  sulphurous  acid,  which 
is  easily  recognised  by  its  characteristic  pungent  odour. 

By  roasting  a  finely  powdered  mineral  in  an  open  tube 
sulphurous  acid  will  be  evolved,  and  if  the  odour  is  not 
perceptible  the  presence  of  sulphur  will  be  ascertained 
by  inserting  a  small  strip  of  moistened  litmus  paper. 


78  QUALITATIVE  DETERMINATION.  PART  II. 

According  to  Plattner,  in  some  cases  even  a  very  little 
sulphur  may  be  detected  by  fusing  the  powdered  substance 
with  2  parts  of  soda  and  1  part  of  borax  on  charcoal  in  E.F., 
provided  no  selenium  is  present.  In  the  case  of  easily 
fusible  metals  which  contain  only  finely  disseminated 
sulphides  and  cannot  be  pulverised — e.g.  raw  lead,  black 
copper,  &c. — a  fragment  of  the  size  of  the  mustard  seed  or 
small  peppercorn  is  used.  In  case  of  metals  that  fuse 
with  difficulty,  as  raw  iron,  the  amount  may  be  obtained 
by  filing. 

When  the  powdered  substance  is  fused  with  soda  and 
borax  in  K.F.  on  charcoal,  sulphide  of  sodium  is  formed, 
which  leaves  a  sulphur  reaction  when  the  fused  mass 
is  removed  from  the  charcoal,  pulverised,  and  placed 
on  a  bright  sheet  of  silver  (a  silver  coin  will  do),  and 
moistened  with  water.  Sulphuretted  hydrogen  is  evolved, 
which  colours  the  silver  black  with  sulphide  of  silver  if  a 
notable  amount  of  sulphur  is  present,  but  if  less  is  present 
only  dark  brown  or  yellow. 

A  minute  trace  of  sulphur  can  be  detected  in  water 
made  acid  (by  a  small  addition  of  nitric  acid)  and  then 
adding  a  little  nitrate  of  baryta  in  a  test  tube.  If 
sulphur  is  present  a  fine  white  precipitate  of  baryta  is 
thrown  down.  The  precipitation  is  greatly  facilitated  by 
slightly  warming  over  the  spirit  lamp. 

PHOSPHORUS. 

Phosphoric  acid  imparts  a  green  colour  to  the 
flame,  especially  after  having  been  moistened  with  sul- 
phuric acid.  This  test  is,  however,  not  always  conclu- 
sive. 

Crush  up  and  then  ignite  the  assay  to  expel  any  mois- 
ture ;  place  in  a  tube  with  a  little  magnesium  wire,  close 


PART  II.  PHOSPHORUS.  79 

the  tube  entirely,  heat  strongly.  Magnesium  phosphide  is 
the  result. 

When  the  fused  mass  is  treated  with  water  and  broken 
up  the  characteristic  odour  of  phosphoretted  hydrogen  is 
evolved. 

Pig  iron  may  be  examined  for  phosphorus  by  dissolving 
a  fragment  in  nitric  acid  ;  then  evaporating  to  dryness  in 
a  porcelain  dish,  heat  it  strongly,  and  then  test  for 
phosphoric  acid  as  directed  above. 

Substances  consisting  of  earths,  metallic  oxides,  iron 
ore,  &c.,  are  tested  by  intimately  mixing  (after  they  have 
been  ground  to  a  fine  powder)  with  5  parts  by  volume  of  a 
previously  prepared  mixture  (4  parts  by  weight  of  soda 
and  1  of  silica)  in  the  agate  mortar,  and  transferring  it  to 
a  soda-paper  cornet  and  fusing  it  in  O.F.  to  a  clear  bead. 
(In  case  of  iron  ores  it  is  best  to  take  4  assays  of  about 
0*5  grain  each  and  afterwards  treat  as  one  globule.) 

The  bead  is  pulverised  in  the  steel  mortar,  and  the 
powder  boiled  in  a  small  porcelain  dish  with  water. 
Phosphate  of  soda,  also  the  excess  of  soda,  are  dissolved. 
The  clear  liquid  is  either  filtered  or  carefully  decanted 
from  the  insoluble  matter  and  removed  into  a  small  porce- 
lain dish.  If  much  silica  has  been  dissolved  and  remains 
in  the  clear  liquid,  add  a  little  carbonate  of  ammonia, 
boil,  and  the  silica  will  be  separated  in  a  gelatinous  form. 

Filter,  and  to  the  filtrate  add  an  excess  of  acetic  acid, 
then  some  acetate  of  lead,  stir,  and  if  the  phosphoric  acid 
amounts  to  several  per  cent,  a  white  precipitate  of  phos- 
phate of  lead  is  at  once  formed,  which  is  collected  on  a 
filter,  dried,  and  fused  in  a  shallow  cavity  on  charcoal. 

If  the  precipitate  has  been  well  washed  a  white  or 
yellowish  globule  with  a  crystalline  surface  is  obtained. 

When  the  precipitate  formed  by  acetate  of  lead  is  so 
trifling  that  it  cannot  be  removed  without  partially  de- 


80  QUALITATIVE  DETERMINATION.  PA«T  II. 

stroying  the  filter,  a  drop  of  dilute  sulphuric  acid  must 
be  added,  which  produces  a  mixture  of  sulphate  and  phos- 
phate of  lead  in  such  quantity  that  it  may  readily  be 
transferred  from  the  filter  to  charcoal. 

When  this  is  fused  by  the  blowpipe  the  sulphate  is 
reduced  partly  to  sulphide  of  lead,  which  soon  volatilises, 
and  partly  to  metallic  lead,  which  gradually  volatilises, 
leaving  small  globules  of  phosphate  of  lead  that  can  be 
recognised  with  the  aid  of  the  magnifying  glass  by  reason 
of  its  characteristic  qualities. 

ARSENIC. 

Arsenic  on  charcoal  evolves  an  unmistakable  smell  of 
garlic.  A  slight  grey  incrustation  is  formed  some  distance 
from  the  assay,  which  in  K.F.  disappears,  assuming  a  faint 
blue  tinge. 

Metallic  arsenides,  if  heated  on  charcoal  with  E.F., 
yield  part  of  their  arsenic,  which  volatilises,  forming  a 
coat  of  arsenious  acid.  If  a  large  amount  of  arsenic  is 
present  greyish  white  fumes  are  evolved,  and  the  odour  of 
garlic  is  recognised  without  stopping  the  blast.  If  the 
latter  is  not  recognised  the  glowing  assay  must  be  held 
directly  under  the  nose,  so  that  the  smallest  quantity  of 
escaping  arsenic  may  be  recognised. 

In  cases  of  nickel  and  cobalt  ores  when  arsenic  is 
separated  with  difficulty,  fuse  the  compound  with  lead  in 
O.F.  on  charcoal,  and  the  presence  of  the  volatilising 
arsenic  will  be  ascertained  by  its  odour. 

Provided  the  quantity  of  arsenic  is  very  small  in  a 
metallic  compound  the  following  process  must  be  resorted 
to:  brittle  metals  are  pulverised  to  powder  ;  malleable 
ones  are  reduced  by  filing : — 

Mix  1  grain  with  6  volumes  of  nitre  and  ignite  in  the 


PART  II.  AKSENIC.  81 

platinum  spoon  with  the  blowpipe  flame  until  no  metallic 
particles  are  visible.  Arsenic  acid  is  formed,  which  com- 
bines with  the  potassa.  The  other  metals  are  oxidised 
and  nitrous  acid  is  liberated.  The  mass  in  the  spoon  is 
now  digested  with  water  in  a  beaker  glass  over  the  spirit 
lamp,  until  everything  is  removed  from  the  spoon. 

The  clear  solution  is  poured  off  from  the  oxides  into  a 
small  porcelain  vessel,  acidified  with  hydrochloric  acid, 
about  0*7  grain  sulphate  of  magnesia  dissolved  in  it  by 
heating  slightly,  an  excess  of  ammonia  added,  and  the 
whole  heated  to  boiling. 

Arseniate  of  ammonia  and  magnesia  separate  and  settle 
quickly  when  the  vessel  is  removed  from  the  flame.  The 
clear  fluid  is  decanted  from  the  precipitate,  which  is  washed 
in  strong  water  of  ammonia,  again  allowed  to  settle, 
and  freed  by  decantation  from  the  fluid,  after  which  it  is 
dried  in  the  vessel.  The  dry  salt  is  mixed  with  6  volumes 
of  a  mixture  of  cyanide  of  potassium  and  soda  in  equal 
parts,  then  treated  (1)  on  charcoal  or  (2)  in  a  matrass  with  a 
narrow  neck.  In  the  former  case  it  is  fused  in  R.F.,  and 
the  volatilised  arsenic  detected  by  the  odour.  In  the 
latter  case  it  is  first  warmed  over  the  spirit  lamp  in  the 
matrass,  to  expel  any  traces  of  moisture  (which  are  collected 
by  an  inserted  roll  of  blotting  paper),  after  F  49 
which  the  mixture  is  heated  to  fusion. 

The  arsenic  acid  is  reduced,  and  forms 
a  sublimate  of  metallic  arsenic  in  the  neck 
of  the  matrass  a  (fig.  49).  If  the  amount 
of  the  arsenic  is  too  small  to  produce  a 
distinct  mirror,  cut  off  the  neck  above 
the  sublimate  with  a  file,  then  hold  the  portion  of  the 
matrass  containing  the  sublimate  in  the  flame.  If  the 
sublimate  consists  of  arsenic  it  will  volatilise  and  yield 
the  arsenic  odour. 

G 


82  QUALITATIVE   DETERMINATION.  PART  II. 

Oxide  of  antimony  (antimonious  acid),  containing  less 
than  -poVo  part  of  arsenic  when  heated  to  redness  in  a  nar- 
row-necked matrass  with  3  volumes  of  neutral  oxalate  of 
potash  and  1  volume  of  charcoal  dust,  will  afford  a  very 
distinct  mirror,  which  on  further  treatment  in  the  spirit 
flame  is  volatilised  with  an  unmistakable  odour. 

CARBON. 

Pure  carbon  (diamond)  in  a  fine  state  of  division 
glows  like  coal  and  burns  slowly  if  placed  on  a  piece  of 
platinum  foil  and  the  flame  directed  down  on  it.  It  is 
consumed,  the  product  of  combustion  being  carbonic  acid. 

Coal,  anthracite,  graphite,  asphaltum,  amber,  &c., 
and  all  such  compounds  of  carbon  volatilise  when  heated 
in  the  platinum  spoon,  first  with  a  mild  O.F.  and  then 
with  a  strong  K.F.,  leaving  nothing  but  silica,  lime,  and 
other  non-volatile  elements.  Minerals  containing  carbonic 
acid  are  easily  tested,  and  with  great  certainty,  by  crushing 
them  up  finely  and  adding  a  little  dilute  nitric  acid  to 
them  in  a  glass  vessel  and  observing  whether  any  effer- 
vescence ensues.  The  glass  should  be  slightly  heated  if 
no  gas  is  evolved.  If  carbonic  acid  exists  in  a  large 
amount  the  effervescence  is  most  violent. 

In  raw  iron,  steel,  and  brass,  the  carbon  (no  matter 
how  combined)  is  easily  found  by  digesting  a  small  frag- 
ment in  a  porcelain  dish  with  about  6  times  its  weight  of 
fused  chloride  of  silver  and  some  water  acidulated  with 
a  few  drops  of  hydrochloric  acid,  leaving  the  whole  covered 
with  a  watch  glass  until  all  the  iron  is  dissolved.  The 
iron  is  converted  into  protochloride,  the  carbon  remains 
behind,  and  a  corresponding  amount  of  silver  is  reduced. 

As  the  carbon  compounds  may  contain  earthy  matter, 
they  must  be  dried,  mixed  with  3  parts  of  antimoniate  of 


PART  II.  CARBON,   BORON,   AND   SILICIUM.  83 

potash,  then  heated  to  redness  in  a  matrass  over  the  spirit 
lamp.  The  carbon  is  oxidised  at  the  expense  of  the  anti- 
monic  acid,  forming  carbonic  acid,  which  combines  with  the 
liberated  potassa.  When  cold,  fill  the  matrass  nearly  to 
the  neck  with  water,  which  is  gradually  heated  to  boiling. 
The  carbonate  and  sulphate  of  potash  dissolve  with  part  of 
the  undecomposed  antimoniate  of  potash,  whilst  most  of  the 
latter  remains  with  the  earths  and  metallic  oxides. 

To  the  warm  solution  a  few  drops  of  nitric  acid  are 
added,  which  causes  effervescence,  more  or  less  lively, 
according  to  the  amount  of  carbonic  acid  present.  Not  a 
bubble  ascends  if  the  substance  contains  no  carbonic  acid, 
but  several  will  be  seen  when  the  most  trifling  amount  is 
present. 

BORON 

Is  a  substance  found  in  nature  combined  with  water, 
soda,  ammonia,  and  metallic  oxides,  and  never  native. 

Turner  has  proposed  a  test  for  boracic  acid  in  salts 
and  minerals  as  follows : — The  fine  powder  is  mixed  to  a 
paste  with  a  little  water  and  1  part  of  a  flux  (it  is  better 
to  employ  3  parts  to  obtain  a  reliable  test),  consisting  of 
4^  parts  bisulphate  of  potash  and  1  part  of  finely  powdered 
fluor  spar  perfectly  free  from  boracic  acid.  It  is  then  fused 
on  a  platinum  wire  within  the  blue  flame,  and  as  soon  as 
the  water  is  expelled  fluoboracis  acid  is  found,  which  is 
volatilised  and  imparts  a  yellowish  green  tinge  to  the  flame. 
This  colour  is  very  transient,  however,  and  must  be  looked 
for  with  great  attention  if  little  boracic  acid  is  present. 

SILICIUM. 

Silicic  acid,  in  the  forms  commonly  known  as  quartz, 
flint,  &c.,  is  infusible  before  the  blowpipe.  It  dissolves 
(when  powdered  finely)  slowly  in  borax  to  a  clear,  diffi- 
cultly fusible  glass,  which  while  hot  is  frequently  co- 

G    2 


84  QUALITATIVE  DETERMINATION.  PART  II. 

loured  by  the  metallic  oxides  present.  It  is  scarcely  at- 
tacked by  phosphate  salt ;  with  soda  it  fuses  to  a  clear 
glass  with  effervescence. 

Both  naturaland  artificial  silicates  can  be  tested  by 
fusing  a  bead  of  phosphate  salt  on  a  platinum  wire,  then 
adding  a  splinter  of  the  silicate  and  treating  it  in  0  F. 
The  bases  dissolve,  leaving  a  silica  skeleton,  which  floats  in 
the  hot,  clear  bead. 

Quartz  rocks  and  all  such  directly  infusible  and 
insoluble  compounds  of  silica  should  be  treated  in  the 
following  manner  : — 

One  part,  very  finely  powdered,  is  fused  with  four  times 
its  weight  of  carbonate  of  soda  in  the  platinum  spoon.  When 
fused,  remove  to  a  small  beaker  glass  and  add  about  20  times 
its  volume  of  water,  then  add  hydrochloric  acid,  enough  to 
make  the  solution  a  weak  one.  Warm  the  beaker  over  the 
spirit  lamp  until  the  solution  has  been  effected  and  the 
carbonic  acid  gas  expelled ;  remove  to  a  porcelain  dish  and 
evaporate  to  dryness.  When  cold,  moisten  with  hydro- 
chloric acid,  allow  it  to  stand  a  short  time,  then  dilute 
with  hot  water,  stir,  allow  to  deposit,  then  decant  the 
fluid,  and  again  treat  the  residue  with  warm  water,  after 
which  filter  and  dry.  Kemove  the  fine  white  precipitate, 
which  is  pure  silicic  acid. 

The  silicium  in  raw  iron,  steel,  brass,  &c.,  is  easily  se- 
parated by  dissolving  a  fragment  in  nitric  acid,  which  holds 
in  solution  the  metallic  oxides  formed  and  leaves  the  silica 
in  a  fine  white  powder,  which  should  be  tested  by  fusing 
with  soda  on  coal.  If  the  powder  contains  silica,  it  will 
be  dissolved  in  the  soda  with  effervescence. 

GLUCINIUM. 

Glucina  alone  is  unchanged  before  the  blowpipe.     In 


PART  II.  GLUCINIUM   AND   LANTHANUM.  85 

borax  it  dissolves  in  considerable  quantity,  forming  a  clear 
glass,  which  by  flaming  becomes  milk  white,  as  it  does  on 
cooling  when  fully  saturated.  In  phosphate  salt  it  dis- 
solves with  the  same  reactions  as  borax.  With  soda  on 
charcoal  it  is  unchanged.  With  nitrate  of  cobalt  it  shows 
a  faint  bluish  grey  colour. 

The  blowpipe  characters  of  glucina  are  not  sufficiently 
prominent  to  admit  of  its  being  recognised  in  such  minerals 
as  contain  it ;  therefore  it  must  be  detected  by  the  humid 
analysis.  To  detect  glucina  the  finely  powdered  mineral 
must  be  dissolved  in  hydrochloric  acid,  then  evaporated  to 
dryness,  the  residue  moistened  with  hydrochloric  acid,  dis- 
solved in  boiling  water,  and  the  silica  filtered  out.  The  acid 
solution  is  made  slightly  anmoniacal,  when  glucina  and 
any  traces  of  sesquioxide  of  iron  are  thrown  down.  They 
are  collected  on  a  filter,  washed  thoroughly,  and  heated 
while  moist  with  a  solution  of  potassa,  until  the  glucina  is 
redissolved  and  the  iron  remains  behind.  After  diluting 
the  solution  with  water,  filtering  it,  and  making  it  slightly 
acid  with  hydrochloric  acid  the  glucina  can  be  again  thrown 
down  with  ammonia,  and  may  then  be  tested  for  alumina. 
Filter,  thoroughly  wash,  and  shake  in  a  test  tube  with  an 
excess  of  carbonate  of  ammonia  solution,  which  dissolves 
the  glucina,  leaving  the  alumina.  On  boiling  the  am- 
moniacal  solution  the  glucina  goes  down  as  a  carbonate, 
and  this  can  be  converted  into  pure  glucina  by  ignition 
in  the  platinum  capsule. 

LANTHANUM. 

The  oxide  alone  on  charcoal  is  not  changed. 

With  borax  in  O.F.  it  dissolves  to  a  transparent  colour- 
less glass,  which,  if  dissolved  in  a  sufficient  quantity,  can  be 
flamed  enamel  white.  If  saturated,  the  glass  of  itself,  on 
cooling,  becomes  enamel  white. 


86  QUALITATIVE  DETERMINATION.  PART  II. 

In  E.F.  with  borax  it  reacts  the  same  as  in  O.F. 

With  phosphate  it  acts  the  same  as  with  borax.  With 
soda  on  charcoal  the  soda  is  absorbed,  and  the  oxide  remains 
with  a  greyish  colour  behind.  As  lanthanum  is  generally 
found  combined  with  cerium  and  didymium  the  exact 
determination  of  it  must  be  referred  to  the  laboratory. 

For  humid  assay  see  Cerium,  p.  89. 

YTTRIUM 

Before  the  blowpipe  is  unchanged. 

On  borax  it  dissolves  to  a  clear  glass  bead,  which  by 
flaming  becomes  milk  white  as  well  as  on  cooling  if  fully 
saturated. 

With  phosphate  salt  it  presents  the  same  reactions  as 
with  borax. 

With  soda  on  charcoal  it  is  unchanged. 

Yttrium  is  but  rarely  met  with,  and  then  nearly  always 
in  common  with  erbium  in  various  combinations.  The 
wet  way  must  be  employed  to  correctly  distinguish  this 
element. 

TERBIUM. 

The  oxide  is  unchanged  before  the  blowpipe.  In  borax 
it  dissolves  to  a  transparent  glass,  rendered  milk  white  on 
naming  or  on  cooling,  when  sufficiently  saturated. 

In  phosphate  glass  it  presents  the  same  reactions  as  in 
borax. 

With  soda  on  charcoal  it  does  not  change.  It  must  be 
determined  by  the  wet  way. 

TANTALUM. 

Tantalic    acid    in    O.F.    alone    on    charcoal   becomes 


PART  II.         TANTALUM,   URANIUM,   AND   TUNGSTEN.  87 

slightly  yellow,  but  is  white  again  when  cold.  In  E.F.  the 
same. 

With  borax  on  platinum  wire  it  dissolves  easily  to  a 
clear  glass,  which  with  a  certain  amount  appears  yellowish 
while  hot,  colourless  on  cooling,  and  can  be  made  opaque 
by  naming.  With  still  more  the  glass  becomes  enamel 
white  on  cooling.  In  E.F.  the  same  as  in  O.F. 

With  phosphate  salt  in  O.F.  it  dissolves  largely  to  a 
clear  glass,  which  with  a  very  large  amount  is  yellowish 
while  hot,  but  colourless  on  cooling.  In  E.F.  the  above 
glass  undergoes  no  alteration. 

With  soda  in  O.F.  with  a  little  more  than  its  volume  of 
soda  it  fuses  on  charcoal  with  effervescence  and  soon  spreads 
out,  and  with  more  soda  it  sinks  into  the  coal.  In  the  E.F.  the 
same  reaction  takes  place  and  it  cannot  be  reduced  to  metal. 

The  wet  way  must  be  employed  for  its  compounds. 

URANIUM. 

The  sesquioxide  of  uranium,  when  heated  in  O.F.  with 
phosphate  salt,  yields  a  yellow  glass,  which  becomes  yellow- 
ish green  on  cooling  and  pure  green  in  E.F. 

This  test  is  a  very  good  one  ;  but  when  oxides  of  iron, 
and  probably  titanic  acid,  are  present  the  phosphate  bead 
becomes  red  on  cooling,  and  the  uranium  colour  can  only 
be  perceived  by  treating  the  glass  in  O.F.,  when  it  assumes, 
on  cooling,  a  green  colour  mixed  with  much  yellow. 

Any  further  examination  must  be  made  by  the  wet 
way. 

TUNGSTEN. 

Tungstite,  according  to  Von  Kobell,  acts  before  the 
blowpipe  as  follows  : — 

On  charcoal  in  E.F.  it  becomes  black. 

In  phosphate  salt  in  O.F.  it  dissolves  to  a  colourless 


88  QUALITATIVE  DETERMINATION.  PART  II. 

or  yellowish  glass,  which  in  E.F.  becomes  fine  blue  when 
cold. 

Tungstic  acid  can  be  easily  recognised  by  its  examina- 
tion with  phosphate  salt.  The  bead  in  E.F.  becomes  blue 
when  cold,  or  in  the  presence  of  iron  more  or  less  red. 

The  presence  of  tungstic  acid  in  tin  slags  may  be 
recognised  by  the  deep  indigo  blue  solution  which  is 
formed  when  the  pulverised  slag  is  warmed  in  a  test  tube 
with  hydrochloric  acid. 

VANADIUM. 

Vanadic  acid  alone  on  charcoal  fuses,  is  reduced,  and 
goes  partly  into  the  coal ;  the  remainder  assumes  the 
colour  and  lustre  of  graphite  and  is  protoxide  of  vanadium. 

With  borax  on  platinum  wire  in  O.F.  it  dissolves  to  a 
clear,  colourless  glass,  but  with  more  it  gives  a  yellow  glass, 
yellowish  green  on  cooling.  In  E.F.  the  above  glass 
changes,  appearing  brownish  when  hot  and  fine  chrome 
green  on  cooling. 

With  phosphate  salt  on  platinum  wire  in  O.F.  it 
dissolves  to  a  clear  glass ;  if  not  in  too  small  a  quantity, 
dark  yellow  while  hot,  and  light  yellow  on  cooling.  In 
E.F.  the  same  as  with  borax. 

Vanadium  is  a  very  rare  metal,  and  has  only  been 
found  as  an  acid  in  a  very  few  minerals.  The  further 
examination  must  be  made  by  means  of  a  humid  analysis. 

PALLADIUM. 

Protoxide  of  palladium  is  reduced  at  a  red  heat,  but 
the  metallic  particles  are  infusible. 

In  O.F.  and  E.F.  on  charcoal  with  borax  the  metallic 
oxides  are  reduced  without  dissolving,  and  a  metallic 
button  cannot  be  obtained. 


PART  II.        PALLADIUM,   RUTHENIUM,   AND   CERIUM.  89 

With  phosphate  salt  the  same  as  with  borax. 

With  soda  on  charcoal  the  soda  sinks  into  the  coal, 
leaving  the  palladium  as  an  infusible  powder. 

Palladium  reduced  from  its  oxides  behaves,  according 
to  Berzelius,  as  follows  : — 

6  Carefully  heated  on  platinum  foil  to  low  redness,  it 
acquires  upon  the  surface  a  blue  colour,  which,  however, 
disappears  at  full  redness. 

4  On  charcoal  alone  it  is  infusible  and  unchangeable. 
With  sulphur  in  K.F.  it  fuses,  but  in  O.F.  the  sulphur 
burns  off,  leaving  the  palladium  behind.  When  fused 
with  bisulphate  of  potash  in  a  sufficiently  large  matrass 
it  is  dissolved  with  evolution  of  sulphurous  acid.  The 
salt  appears  yellow  when  cool.' 

RUTHENIUM. 

This  metal  is  only  found  in  small  quantities  in  native 
platinum,  and  is  grey  white,  brittle,  and  very  infusible. 
It  is  not  attacked  by  fusing  with  bisulphate  of  potash, 
and  is  scarcely  acted  upon  by  aqua  regia.  No  characteristic 
blowpipe  reactions  can  be  obtained  from  this  metal. 

CERIUM. 

Before  the  blowpipe  on  charcoal  the  protoxide  is 
changed  by  O.F.  into  the  sesquioxide,  which  remains 
unchanged  even  in  R.F. 

In  borax  with  O.F.  it  is  soluble  to  a  dark  yellow  or  red 
glass  (similar  to  the  sesquioxide  of  iron  glass),  but  in  cool- 
ing it  is  yellow.  If  sufficiently  saturated  the  glass  can  be 
flamed  opalescent,  and  if  fully  saturated  it  becomes  so  of 
itself  on  cooling. 

In  R.F.  the   yellow  glass  becomes  colourless,  and    a 


90  QUALITATIVE  DETERMINATION,  PART  II. 

strongly  saturated  glass  on  cooling  becomes  enamel  white 
and  crystalline. 

In  O.F.  with  phosphate  glass  it  reacts  the  same  as  with 
borax,  but  the  colour  disappears  entirely  on  cooling.  In  E.F. 
no  saturation  prevents  the  glass  being  transparent.  It  is 
colourless  both  w^hilst  hot  and  cold  (which  distinguishes 
oxide  of  cerium  from  oxide  of  iron). 

With  soda  on  charcoal  the  soda  is  absorbed,  and  the 
oxide  is  reduced  to  protoxide,  which  remains  behind,  of  a 
light  grey  colour. 

As  cerium,  lanthanum,  and  didymium  are  generally 
combined  together,  the  following  simple  method  is  given 
to  enable  the  assay er  to  determine  all  three : — The  mixed 
oxides,  after  having  been  ignited,  are  first  treated  with 
weak,  then  with  concentrated  nitric  acid,  which  extracts  the 
lanthanum  and  didymium.  Upon  evaporating  this  solution, 
igniting  the  salt,  and  again  treating  the  oxides  with  very 
dilute  nitric  acid,  any  oxide  of  cerium  which  has  been 
dissolved  now  remains  undissolved. 

From  the  solution  of  lanthanum  and  didymium  the 
oxide^  are  thrown  down  with  ammonia  and  dissolved  in 
sulphuric  acid.  The  dry  salt  being  then  dissolved  to 
saturation  in  water  at  43°  to  45°  Fahr.,  and  the  solution 
then  warmed  to  100°,  sulphate  of  lanthanum  separates, 
leaving  the  didymium  salt  in  the  solution,  from  which  it 
can  be  precipitated  by  potassa.  The  oxides  may  be 
obtained  still  purer  by  repeating  the  process. 

DIDYMIUM. 

The  oxide  on  charcoal  in  O.F.  is  unchanged,  but  in  E.F. 
with  a  strong  heat  it  loses  its  brown  colour  and  becomes 
grey.  In  borax  with  O.F.  it  dissolves  to  a  clear  glass  of 
a  dark  amethyst  colour. 


PART  II.  DIDYMIUM,   ERBIUM,   AND  NIOBIUM.  91 

In  phosphate  salt  it  behaves  the  same  as  with  borax. 
With    soda  on  charcoal   it  is  insoluble ;  the    soda  is 
absorbed  and  the  oxide  remains  of  a  grey  colour. 

For  a  minute  examination  see  assay  of  cerium,  p.  90. 


ERBIUM. 

The  yellow  oxide  in  R.F.  becomes  lighter  in  colour  and 
translucent  in  appearance. 

In  borax  it  dissolves  with  difficulty  to  a  colourless  glass, 
which  by  naming,  and  also  when  saturated,  is  milk  white. 

With  phosphate  salt  the  same  reactions  as  with  borax. 

With  soda  on  charcoal  it  is  unaltered. 

The  humid  method  must  be  employed  for  any  further 
examinations  of  erbium. 

NIOBIUM,  or  COLUMBIUM. 

Niobic  acid,  before  the  blowpipe  on  charcoal  in  O.F., 
becomes  yellowish,  but  is  white  again  on  cooling.  In 
R.F.  the  same. 

With  borax  in  O.F.  on  platinum  wire  it  dissolves 
easily  to  a  clear,  colourless  glass,  becoming  opaque  by  flam- 
ing with  a  moderate  addition,  and  with  more  becomes 
opaque  when  cool.  In  R.F.  yields  a  glass  which,  after 
treatment  in  O.F.,  becomes  opaque  of  itself,  and  on 
cooling  remains  unaltered. 

With  phosphate  salt  on  platinum  wire  in  O.F.  it  dis- 
solves largely  to  a  clear  glass,  yellow  while  hot,  but  colour- 
less on  cooling. 

In  R.F.  with  a  very  large  addition  the  glass  becomes 
brown.  The  addition  of  sulphate  of  iron  causes  a  blood 
red  bead. 

With  soda  in  O.F.  fuses  with  an  equal  volume  of  soda, 


92  QUALITATIVE  DETERMINATION.  PAET  II. 

with  effervescence,  but  with  more  soda  goes  into  the  coal. 
In  E.F.  the  same,  and  it  cannot  be  reduced  to  metal. 

The  wet  way  must  be  employed  for  an  accurate  deter- 
mination. 

THORIUM. 

Thoria  alone  before  the  blowpipe  remains  unaltered. 
With  borax  on  platinum  wire  it  dissolves  in  small  quantity 
to  a  clear  glass,  milk  white  on  cooling,  if  saturated,  but  if 
it  appears  clear  on  cooling  it  cannot  be  made  opaque  by 
flaming. 

With  phosphate  salt,  same  as  with  borax.  With  soda 
on  charcoal  it  is  insoluble. 

Thorium  is  a  rare  element,  seldom  met  with,  and  as 
it  gives  no  characteristic  blowpipe  reaction  the  humid 
analysis  must  be  employed. 

THALLIUM. 

Thallium  melts  very  easily  on  charcoal,  and  when 
touched  with  the  point  of  the  blue  flame  the  metal  is 
surrounded  by  a  green  flame. 

When  being  fused  on  charcoal  a  moderate  amount  of 
white  coat  of  oxide  is  formed  at  some  distance  from  the 
assay,  which  is  driven  off  when  E.F.  is  applied. 

Its  salts  also  give  an  intense  green  flame. 

With  the  spectroscope  it  can  be  readily  determined. 

MOLYBDENUM. 

When  molybdic  acid  is  heated  on  charcoal  in  O.F. 
it  volatilises ;  at  the  same  time  the  support  acquires  a 
yellow  coating,  often  crystalline,  which  becomes  white 
on  cooling.  In  R.F.  metallic  molybdenum  is  formed, 
which  may  be  obtained  as  a  grey  powder  by  washing 


PART  II.  MOLYBDENUM,   ETC.  93 

the  pulverised  charcoal.  Sulphide  of  molybdenum,  when 
heated  in  O.F.,  yields  sulphurous  acid  gas  and  a  sub- 
limate of  molybdic  acid. 

In  order  to  find  a  small  amount  of  molybdenum  in  its 
compounds  it  is  necessary  to  have  recourse  to  the  wet  way. 

RHODIUM. 

Rhodium  gives  no  characteristic  reactions  with  the 
blowpipe. 

IRIDIUM. 

Iridium  before  the  blowpipe  cannot  be  determined. 
It  can  be  separated  from  platinum,  gold,  silver,  copper,  &c., 
by  following  the  method  laid  out  in  the  gold  assay  (Class 
B,  /),  and  the  percentage  estimated. 

OSMIUM. 

Osmium  generally  occurs  with  platinum  and  iridium, 
&c.,  and  forms,  with  iridium,  iridosmine. 

The  metal  as  well  as  the  protoxide  and  binoxide  change 
easily,  when  heated  in  the  air,  to  osmic  acid,  which  is 
volatile  and  recognisable  by  its  highly  characteristic, 
penetrating,  and  disagreeable  odour,  resembling  that  of 
chlorine  and  bromine.  If  osmium  be  placed  on  a  strip  of 
platinum  and  brought  into  the  outer  flame  at  half  its 
height,  the  flame  becomes  intensely  luminous. 

For  minute  portions  the  wet  method  must  be  employed. 

SELENIUM. 

Selenium,  even  when  combined  with  other  elements,  is 
easily  determined  by  heating  on  charcoal,  when  it  evolves 
a  strong  odour  of  bad  horse-radish.  When  heated  in  a 
glass  tube  selenium  forms  a  red  sublimate. 


94  QUALITATIVE   DETERMINATION.  PART  II. 

Selenium,  when  fused  within  the  blue  flame  on  coal, 
volatilises  with  an  intense  azure  blue  flame. 

The  salts  of  selenium  (selenates  and  selenites)  are  re- 
duced in  E.F.  on  coal,  either  alone  or  with  addition  of  soda, 
to  selenides,  which  emit  a  distinct  horse-radish  odour. 

TELLURIUM. 

Tellurium  is  very  rare,  and  is  found  alloyed  with  other 
elements  and  as  tellurous  acid  in  tellurite.  It  is  a 
white,  brittle,  and  easily  fusible  metal.  It  sublimes  in  a 
glass  tube  over  the  lamp.  Heated  on  charcoal,  it  burns 
with  a  greenish  blue  flame,  with  production  of  dense  white 
vapours  of  tellurous  acid. 

ZIRCONIUM. 

Zirconia  is  infusible  and  unchanged  by  either  E.F.  or 
O.F. 

If  prepared  from  the  sulphate  and  heated  by  a  blow- 
pipe it  becomes  so  brilliant  that  it  dazzles  the  eye,  and 
in  this  property  it  exceeds  any  other  substance. 

In  borax  it  dissolves  to  a  transparent  glass,  which 
becomes  on  flaming,  or  if  saturated  on  cooling,  milk  white. 

In  phosphate  glass  it  dissolves  slower  than  in  borax, 
and  gives  quickly  an  opaque  glass. 

With  soda  on  charcoal  it  is  unchanged. 

With  nitrate  of  cobalt  in  O.F.  it  receives  a  dirty  violet 
colour. 


PAET   III. 


ASSAY    OF    SILVER. 
GOLD. 
MERCURY. 
COPPER. 
LEAD. 
BISMUTH. 
TIN. 
IRON. 
NICKEL. 
COBALT. 

NICKEL  AND  COBALT. 
COAL. 


SILVER. 

ONLY  a  small  proportion  of  the  large  amount  of  silver 
which  is  at  the  present  time  produced  for  commercial 
purposes  is  found  native,  and  then  not  pure,  as  it  is  gene- 
rally alloyed  with  a  little  copper,  gold,  platinum,  mercury, 
arsenic,  iron,  lead,  bismuth,  or  antimony. 

Native  silver  occurs  in  masses  or  in  arborescent  and 
filiform  shapes  in  veins  traversing  gneiss,  schists,  porphyry, 
and  other  rocks  ;  it  also  occurs  disseminated  in  native 
copper  and  galena,  but  usually  invisible  to  the  naked  eye, 
therefore  requiring  the  aid  of  a  good  microscope  to  deter- 
mine its  presence. 

Silver,  when  pure,  has  a  metallic  lustre.  Colour  and 
streak,  silver  white.  Ductile.  Hardness,  2-5-  3.  Specific 
gravity  when  pure,  1O5.  Minerals  containing  silver  are 
found  in  veins  of  nearly  all  descriptions,  and  even  in  sea 
water  minute  traces  have  been  found  by  a  careful  ana- 
lysis. 

The  principal  minerals  containing  silver  are  as 
follows : — 

Argentite :    silver   glance,   containing    87    per   cent, 
silver,  with  sulphur. 

Stephanite :  brittle  silver  ore,  containing  68  per  cent, 
silver,  with  sulphur  and  antimony. 

Proustite:  light  red  silver  ore,  containing  65'4  per 
cent,  silver,  with  sulphur  and  arsenic. 

Pyrargyrite:  dark  red  silver  ore,  containing  59  per 
cent,  silver,  with  sulphur  and  antimony. 
H 


98        ASSAY   OF  SILVER,   GOLD,  MERCUKY,  ETC.      PART  III. 

Argentiferous  grey  copper  ore  (fahlerz),  containing 
from  5-7  to  18-31*8  per  cent,  silver,  with  antimony 
and  sulphur. 
Argentiferous  sulphide  of  copper,  containing  53  per 

cent,  silver,  with  sulphur  and  copper. 
Polybasite,    containing  72-94  per  cent,  silver,  with 

copper,  sulphur,  arsenic,  and  antimony. 
Chilenite,    containing    86*2    per    cent,    silver,    with 

bismuth  13*8  per  cent. 

Bromyrite,  containing  57*4  per  cent,  silver,  with  bro- 
mine 42*6  per  cent. 
Cerargyrite  (horn  or  chloride),  containing  7 5 '3  per 

cent,  silver,  with  chlorine  24-7  per  cent. 
Embolite,    containing    60-72    per  cent,   silver,   with 

bromine  and  chlorine. 
Sternbergite,  containing  33*2  per  cent,  silver,  with  iron 

36  per  cent,  and  sulphur  30  per  cent. 
lodyrite,  containing  46  per  cent,  silver,  with  iodine  54 

per  cent. 
Selenic   silver,   containing   11*6— 42*8— 65*5  per  cent. 

silver,  with  selenium,  copper,  and  lead. 
Hessite,  containing  62 '8  per  cent,  silver,  with  tellurium 

37-2  per  cent. 

Silver  is  a  metal  extensively  used  in  the  arts  and 
manufactories,  and  many  of  their  products  contain  it  in 
more  or  less  proportions. 

Silver  will  be  found  in  the  products  as  well  as  in  the 
refuse  from  nearly  all  lead  and  copper  smelting  works, 
if  carefully  looked  for,  and  a  very  small  amount  can  be 
determined  with  great  accuracy.  Any  mineral,  alloy,  or 
product  containing  what  is  termed  6  a  trace  of  silver,' 
about  ^  ounce  to  the  ton  of  2,000  pounds,  can  be  assayed, 
and  the  metal  extracted  and  determined  with  accuracy  by 
the  following  methods. 


PART  III.  SILVER.  99 

Assay  of  Silver. 

In  order  to  separate  silver  from  its  ores  and  compounds 
by  the  blowpipe  the  previous  metal  must  be  formed  into 
an  alloy  with  lead ;  then  the  silver  lead  concentrated  by 
a  process  known  as  scorification,  by  which  the  bulk  of  the 
lead,  copper,  &c.,  is  oxidised ;  then  the  concentrated  silver 
lead  is  subjected  to  the  process  of  cupellation,  whereby 
all  the  lead  and  other  base  metals  are  oxidised  and  the 
silver  left  in  the  form  of  a  metallic  button. 

Commercial  ores,  especially  very  rich  ones,  frequently 
differ  in  richness  ;  it  is  therefore  advisable  in  all  cases  of 
importance  to  make  two  or  three  assays  of  each  sample, 
and  if  the  results  do  not  agree  to  make  one  or  two  more, 
and  then  to  take  the  mean  or  average  of  the  whole,  and 
to  that  add  the  loss  of  silver  proved  by  the  synthetical 
assay.  In  assays  of  alloys,  proof  and  synthetical  assays 
are  absolutely  necessary  to  prove  the  work. 

Silver  Assay. 

The  assay  of  silver  is  divided  into  three  classes,  A, 
B,  and  C. 

A.  When  the  silver  is  principally  in  combination 
with  non-metallic  bodies. 

(a)  Containing  volatile  matters,  as  sulphur  and  arsenic, 
and  so  combined  as  to  be  decomposed  by  fusion 
with  borax  and  lead  on  charcoal. 

(6)  Containing  sulphides  not  decomposed  by  borax  and 
lead  alone  (argentiferous  sulphides  of  molyb- 
denum). 

(c)  Containing  chlorine,  bromine,  and  iodine,  with  little 

or  no  other  volatile  matters. 

(d)  Consisting  of  metallic  oxides,  easily  reduced  on 

charcoal  (litharge,  &c.) 

(e)  General  method  adapted  to  the  assay  of  a,  6,  c ; 

either  to  one  or  all. 
u  2 


100      ASSAY   OF  SILVER,  GOLD,  MERCURY,  ETC.      PART  III. 

B.  Metallic   alloys   ready  for  cicpellation  after  the 

necessary  addition  of  lead, 
(a)  Bar  and  ingot  silver,  standard  silver,  coins,  native 

silver,  alloys  of  silver,  gold,  and  copper. 
(7.  Metallic   alloys   requiring  either  distillation,  or 

fusion   with  fluxes  before  they  are  ready  for 

cupellation. 

(a)  Containing  mercury  in  the  form  of  amalgam. 
(6)  Test    and    precipitated    silver.       Eetorted    silver 

amalgam. 

(c)  Containing  copper  or  nickel  with  more  or  less  sul- 

phur,  arsenic,    zinc,    black    copper,    brass,  and 
German  silver. 

(d)  Containing  tin  —  argentiferous    tin,   bronze,  bell 

metal,  gun  metal,  and  bronze  coinage. 

(e)  Containing  antimony,  tellurium,  or  zinc. 

(/)  Iron  bears  from  smelting  furnaces  and  silver-steel, 

&c. 

(g)  Containing  alloys  of  lead  or  bismuth  with  silver,  in 
which  the  proportions  of  the  former  predominate. 
(h)  Containing  copper  in  the  form  of  coins,  ingot,  sheet, 
or  wire ;  cement  and  copper  nickel  alloys  con- 
taining silver. 

A.  (a)  Consists  of  most  commercial  ores  which  con- 
tain iron,  copper,  and  arsenical  pyrites,  antimonial  glance, 
blende,  selenides,  silver  glance,  sulphide  of  silver,  ruby 
silver,  sulphide  of  silver  and  copper,  miargyrite,  &c. ;  also 
copper  ores,  as  copper  glance,  purple  copper,  fahlerz,  &c.; 
also  lead  ores,  as  galena,  selenide  of  lead,  &c. ;  also  copper 
and  lead  mattes,  lead  sublimate,  and  cobalt  speiss. 

Reduction  to  Silver  Lead. 

The  ore  is  reduced  to  powder  and  passed  through  a. 
sieve  of  2,000  holes  to  the  linear  inch;  it  is  then  tho- 


PART  111.  SILVEE.  101 

roughly  mixed  and  1*5  grain  weighed  out.  The  ore  is 
fluxed  with  borax  and  lead.  The  amount  of  borax  required 
is  dependent  on  the  fusibility  and  amount  of  matter  to  be 
slagged.  Ores  containing  much  gangue,  iron,  cobalt,  or 
tin  require  1J  grain  borax  glass.  When  ores  contain 
little  gangue  and  much  metallic  sulphides  0*8  to  1*2  grain 
borax  glass  is  quite  sufficient.  Should  the  assay  during 
the  fusion  show  itself  refractory,  a  little  more  borax  may 
be  added  to  it. 

The  amount  of  lead  required  depends  on  the  other 
metals  present  in  the  ore.  A  substance  containing  7  per 
cent,  copper  or  10  per  cent,  nickel  requires  five  times  its 
weight  of  lead  (7 -5  grains),  but  when  it  contains  more 
than  this  amount  the  proportion  must  be  dependent  on  the 
amount  of  copper,  &c.,  present.  When  this  is  not  known 
it  is  in  all  cases  better  to  use  too  much  than  too  little  lead, 
as  in  the  last  case  the  separation  of  the  silver  from  the 
copper  is  not  effected,  and  a  lead  alloy  rich  in  nickel  can- 
not be  cupelled. 

The  following  table  will  show  the  relative  proportions 
to  be  employed  :— 

Copper  glance,    containing  about  80  per  cent,  copper,  requires 

15  times  its  weight  of  lead. 
Covellite,   containing  about  65-66  per    cent,    copper,  requires 

12  times  its  weight  of  lead. 
Purple  copper,  containing  about  55-60  per  cent,  copper,  requires 

11  times  its  weight  of  lead. 
Tennantite,  containing  about  48-50  per  cent,   copper,  requires 

10  times  its  weight  of  lead. 
Kupferblende,  containing  about  41-40  per  cent,  copper,  requires 

10  times  its  weight  of  lead. 
Fahlerz,    containing  about  30-40  per  cent,  copper,  requires  10 

times  its  weight  of  lead. 
Cupreous  bismuth  ore,  containing  about  34-35  per  cent,  copper, 

requires  10  times  its  weight  of  lead. 
Copper    pyrites,    containing    about  30-34    per  cent,    copper, 

requires  10  times  its  weight  of  lead . 


102       ASSAY  OF  SILVER,   GOLD,  MERCURY,   ETC.      PART  III. 


Sulphide  of  copper  and  silver,  containing  about  30-31  per  cent. 

copper,  requires  10  times  its  weight  of  lead. 
Tin  pyrites,  containing  about  29-30  per  cent,  copper,  requires 

7  times  its  weight  of  lead. 
Eukairite,  containing  about  23-25  per  cent,  copper,  requires  7 

times  its  weight  of  lead. 
Bournonite,  containing  about  12-13  per  cent,  copper,  requires 

7  times  its  weight  of  lead. 
Copper  regulus,  containing  up  to  45  per  cent,  copper,  requires 

10  times  its  weight  of  lead. 

Copper  regulus,  containing  up  to  50-60  per  cent,  copper,  re- 
quires 10  times  its  weight  of  lead. 
Lead   speiss,  containing  up  to  10-40  per  cent,  copper,  requires 

10  times  its  weight  of  lead. 
Cobalt  speiss,  containing  up  to  40-50  per  cent,  copper,  requires 

10  times  its  weight  of  lead. 

The  assay  having  been  prepared,  is  poured  with  care  into 
a  soda-paper  cornet,  placed  in  a  charcoal  bore  of  about  T4^ 
FIG  50  (Full  size )  of  an  inch  in  diameter  at  the  bottom, 
and  from  T%  to  -^  at  the  top.  The 
cavity  is  bored  wider  at  the  top,  to 
allow  the  flame  to  reach  down  to  the 
bottom  of  the  bore.  The  top  of  the 
cornet  is  then  closed  up  with  a  pair 
of  pliers  and  pressed  firmly  down 
(see  fig.  50).  The  assay  is  now  in- 
clined towards  the  flame,  and  a  re- 
duction flame,  at  first  moderately 
strong,  is  employed  to  cover  nearly 
all  the  top  of  the  assay.  The  paper, 
is  not  consumed  until  the  par- 
ticles below  it  have  entered  into  fusion  and  prevented 
mechanical  loss.  The  whole  assay  is  now  submitted 
to  a  strong  but  pure  R.F.  at  an  angle  of  30°  to  35° 
degrees.  By  the  action  of  this  flame  a  part  of  the  sulphur, 
arsenic,  antimony,  zinc,  &c.,  is  volatilised,  but  the  greater 


PART  III.  SILVER.  103 

part,  along  with  the  metallic  bases,  unite  with  the  lead  to  a 
globule,  whilst  the  gangue,  the  difficultly  reducible  metals, 
and  a  smaller  part  of  the  easily  oxidisable  but  non-volatile 
metals  (which  have,  been  oxidised  by  the  first  action  of  the 
heat)  combine  with  the  borax  to  form  the  slag.  With  re- 
fractory ores  it  often  appears  as  if  the  slag  were  quite  free 
from  lead  globules;  but  this  is  not  to  be  trusted  to,  as  often, 
under  the  surface  of  the  well-fused  slag,  unacted-upon  par- 
ticles of  the  ore  may  be  concealed,  which  is  only  to  be 
obviated  by  moving  frequently  the  charcoal,  so  as  to  change 
the  portion  of  the  assay ;  this  must  be  done  also  with  easily 
fusible  assays,  as  by  this  means  the  lower  part  of  the  assay 
and  the  carbonised  soda  paper  is  exposed  to  the  flame. 
As  the  paper  is  hardly  acted  upon  in  a  good  R.F.,  it  is 
necessary  to  direct  the  flame  on  to  the  slag,  so  as  to 
cover  it  but  leave  the  paper  on  one  side  with  access 
to  the  air,  by  wilich  it  is  consumed,  while  the  slag  is 
not  affected.  When  consumed,  the  whole  slag  is  again 
covered  by  the  R.F.,  to  reduce  any  litharge  that  may 
have  been  formed,  and  which  by  this  means  is  united  to 
the  main  globule. 

If  the  slag,  after  being  treated  thus  in  the  R.F.  and 
moved  about  several  times,  forms  a  globule  itself,  and 
shows  no  lead  globules,  and  is  perfectly  fluid,  it  may 
be  considered  free  from  silver.  Whilst  the  slag  is 
covered  with  the  E.F.  the  metallic  globule  is  only  touched 
by  the  side  of  the  flame,  to  keep  it  perfectly  fluid  and 
ready  to  take  up  any  straggling  lead  globule  (fig.  51). 
The  assay  is  allowed  to  cool,  and  then  removed  with  the 
pliers  and  placed  between  two  thick  pieces  of  paper  on  the 
steel  anvil  and  broken  up  with  the  hammer;  the  lead 
button  carefully  picked  up  with  the  pliers  and  brushed,  is 
then  ready  for  the  next  process. 

The  finely  crushed  slag  is  washed  in  water  and  then 


104      ASSAY   OF  SILVER,  .GOLD,  MERCURY,  ETC.      PART  III. 


examined  with  the  magnifying  glass,  to  see  if  any  small 
globules  of  lead,  &c.,  remain,  and  if  such  are  found  the 
safest  plan  to  secure  a  perfect  assay  is  to  repeat  the 
operation.  In  assays  of  no  commercial  importance  the 


FIG.  51.     (f  nat.  size.) 


fine  globules  can  be  separated  from  the  slag  by  vanning 
in  water  and  then  adding  them  to  the  main  globule. 

Scorification  and  Concentration  of  the  Silver  Lead. 

If  the  lead  button  is  malleable  the  scorification  can  be 
proceeded  with  direct ;  but  if,  on  the  contrary,  it  is  brittle, 

FIG.  52.     (Full  size.)  from  one  to  three  grains  of 

proof  lead  and  0'3  grain 
borax  glass  is  added  to  it  on 
the  scorifier,  and  the  ope- 
ration carried  on  as  before. 
The  scorification  is  best 
carried  on  in  a  small  scori- 
fier made  of  good  fine  clay,  about  T%-  of  an  inch  in  diameter, 
£  of  an  inch  thick  in  its  deepest  place,  and  1  of  an  inch 
deep  in  the  centre  (see  fig.  52).  It  is  used  in  a  holder  made 
of  fire  clay,  which  is  partially  covered  with  thick,  smooth 
paper  about  2J  inches  long  and  with  a  hollow  place  in 


PART  III. 


SILVER. 


105 


the  top,  in  which  the  scorifier  fits  (see  fig.  53).  A  piece 
of  charcoal  will  also  make  a  good  holder,  and  can  be  readily 
cut  to  the  required  shape.  FIG.  53.  (Full  size.) 

The  scorifier  is  warmed,  and  when  at 
a  red  heat  the  globule  of  silver  lead  is 
added  and  brought  into  a  state  of  fusion 
by  the  use  of  the  K.F.  Then  the 
O.F.  is  used  and  the  heat  applied 
gently.  The  fluid  litharge  soon  forms, 
and  portions  of  which  adhere  and  glaze 
the  sides  of  the  cup.  The  formation  of 
the  litharge  is  greatly  assisted  by  slowly 
turning  the  assay  round  and  round  and 
from  side  to  side  at  a  gentle  inclination, 
and  at  the  same  time  keeping  the  flame 
at  the  edge  of  the  bead. 

When  the  litharge  has  once  formed, 
it  accumulates  rapidly,  and  from  five  to 
ten  minutes  completes  the  operation. 


If  the  ore  is  poor  in  silver  the  scorification  can  be  carried 
on  until  what  is  termed  the  6  eye '  appears,  i.e.  the 
small  button  of  lead  is  nearly  covered  with  litharge  and 
only  just  visible.  The  operator  can,  after  a  few  experi- 
ments, decide  when  the  operation  should  be  discontinued. 
When  the  lead  is  rich  in  silver  it  oxidises  very  slowly 
and  assumes  a  spherical  form. 

The  assay  is  allowed  to  cool,  and  then  the  scorifier  is 
broken  on  the  steel  anvil  and  the  button  carefully  brushed. 
It  is  then  ready  for  cupellation. 

N.B.  Plattner  and  David  Forbes  advise  scorification 
to  be  partially  carried  on,  on  charcoal,  after  the  reduction 
of  the  assay,  and  then  finished  on  a  cupel  of  coarse  bone 
ash.  The  author  has  found  a  loss  of  silver,  as  well  as  an 
occasional  spirting,  &c.,  by  the  prolongation  of  the  assay  on 


1 06      ASSAY  OF  SILVER,   GOLD,    MERCURY,   ETC.      PART  III. 


charcoal  after  the  complete  reduction  of  the  assay  has 
been  effected,  and  for  accuracy  and  despatch  he  recommends 
the  above  method,  as  it  has  been  used  for  some  j/ears  with 
success  by  himself. 

Cupellation. 

When  an  alloy  of  lead,  silver,  gold,  copper,  &c.,  is 
fused  in  a  cupel  in  a  current  of  air,  the  lead  is  readily  oxi- 
dised and  forms  a  very  fusible  oxide.  The  lead  parts  with 
portions  of  its  oxygen  to  the  copper  and  other  base  metals. 
The  oxides  thus  produced  are  dissolved  and  carried  down 
into  the  porous  cupel  in  a  liquid  state  by  the  vitrified 
oxide  of  lead,  leaving  the  silver  and  gold  in  the  form  of  a 
small  globule  on  the  surface  of  the  cupel. 

The  cupellation  is  conducted  as  follows  : — Any  lead 
FIG.  54.  (Full  size.)  alloy  over  5  grains  in  weight  is  best  cupelled 
in  one  of  the  previously  prepared  cupels 
placed  in  the  cupel-holder  (see  fig.  54).  If 
the  weight  is  under  5  grains  a  small  cupel 
is  sufficient,  which  can  be  rapidly  prepared 
by  moistening  some  of  the  finely  powdered 
bone  ash  with  enough  water  to  form  a  dryish 
paste.  The  paste  is  placed  in  the  steel  cupel 
mould  (see  fig.  55),  the  bottom  of  which 
must  either  rest  on  the  steel  anvil  or  some 
hard  solid  substance,  and  a  cupel  formed  by 
placing  the  bolt  (fig.  56)  on  the  top  of  the 
mould  and  applying  a  few  light  strokes.  The 
mould  (fig.  57)  containing  the  cupel  is  now  dried  slowly  over 
the  lamp,  and  finally  heated  to  redness,  and  if  no  cracks  or 
flaws  appear,  and  the  cupel  presents  a  smooth  and  regular 
surface,  the  alloy  can  now  be  added  (it  is  never  advisable 
to  proceed  with  the  cupellation  unless  the  cupel  is  found 
to  be  perfect),  and  a  mild  K.F.  applied  until  the  assay  is 


PART  III. 


SILVER. 


107 


in  a  state  of  fusion ;  directly  it  is  so  the  O.F.  must  be 
applied,  and  the  same  continued  at  the  outer  edge  of  the 
globule,  and  without  touching  the  assay.  A  strong 
enough  heat  must  be  imparted  to  the  bone  ash,  to 
keep  the  assay  .in  oxidation  without  allowing  it  to  become 

FIG.  55.     (Full  size.) 


(Full  size.) 


chilled  or  quiet.  The  cupel  can  also  be  moved  slightly 
from  side  to  side,  which  gives  the  lead  a  fresh  surface  of 
clean  bone  ash  to  act  upon  and  facilitate  the  completion 
of  the  operation.  It  is  best  to  finish  the  assay  about  the 
centre  of  the  cupel,  but  at  the  same  time  it  is  FIG.  56. 
not  absolutely  necessary  for  the  accuracy  of 
the  assay. 

With  a  little  practice  the  operator  can 
tell  when  the  oxidation  is  nearly  finished  by 
the  surfaces  of  the  bead  being  covered  with 
iridescent  colours  (resembling  rainbow  co- 
lours),which  only  last  but  amoment,when  the 
globule  rotates  and  brightens.  Directly  the 
colours  disappear  the  heat  should  be  slightly 
raised,  to  free  the  bead  from  the  last  traces  of 
lead,  and  then  the  assay  is  cooled  down  slowly. 
In  assays  very  poor  in  silver  the  latter  precau- 
tion is  scarcely  necessary.  In  the  case  of  rich  ores,  alloys,  &c., 
much  care  must  be  exercised  in  cooling  the  bead  gradually, 
else  a  violent  spurting  takes  place  and  small  particles  of  the 
silver  are  thrown  out  from  the  bead,  and  the  assay  cannot 
be  relied  upon,  and  it  should  be  repeated.  When  cool  the 
bead  is  removed  with  the  steel  pliers  from  the  cupel  and 


108      ASSAY  OF  SILVER,   GOLD,   MERCURY,  ETC.      PART  III. 


FIG. 57. 
(Full  size.) 


cleaned  from  any  adherent  bone  ash,  and  if  too  small  to 
be  weighed  it  must  be  very  carefully  detached  by  a 
needle  or  some  other  sharp  instrument, 
and  so  as  not  to  injure  its  form.  It  is 
then  measured  or  weighed,  according  to  its 
size,  but  when  the  bead  weighs  more  than 
O'Ol  grain  it  is  more  correctly  estimated 
by  the  balance  than  if  measured.  In 
case  the  ore  is  very  poor,  and  the  button 
found  to  be  very  minute  (on  scale  below 
No.  16,  or  0*11  per  cent.),  it  is  best  to 
make  a  duplicate  assay  and  add  the  first 
button  to  the  silver  lead  on  the  cupel  of  the 
second  assay,  and  when  finished  measure 
or  weigh  both  together. 
The  loss  of  silver  by  reduction.,  scorification,  and 
cupellation  can  be  corrected  by  comparing  the  results  ob- 
tained from  the  ore  or  alloy  with  those  obtained  by  operat- 
ing on  a  carefully  weighed  piece  of  proof  silver.,  which  is 
added  to  an  artificial  compound,  prepared  by  the  operator 
to  resemble  as  nearly  as  possible  the  composition  of  the  ore 
or  alloy  which  has  been  assayed.  The  synthetical  assay,  so 
prepared,  must  be  free  from  silver,  with  the  exception  of 
the  amount  weighed  and  added ;  and  it  should  be  fused, 
scorified,  and  cupelled  in  a  similar  manner  to  the  native 
ore  or  alloy,  and  with  the  same  quantity  of  lead  and  fluxes. 
The  difference  in  weight  of  the  proof  silver  before 
assaying,  and  what  is  found  afterwards,  will  represent  the 
loss  of  silver,  and  it  should  be  added  to  the  assay  weight 
of  the  ore  or  alloy  which  has  been  assayed,  and  it  may  be 
considered  as  the  correct  loss  which  has  taken  place. 

Ores  and  alloys  very  poor  in  silver,  and  so  poor  that  their 
weight  cannot  be  readily  ascertained  by  the  balance,  do  not 
require  any  compensation  to  be  made  for  the  loss  of  silver 
in  cupellation,  &c.,  as  the  loss  on  very  small  beads  is  so 


PART  III.  SILVER.  109 

minute  that  it  can  scarcely  be  estimated  with  accuracy, 
and  even  if  it  could  it  would  be  too  little  to  be  of  any 
commercial  importance. 

Most  accurate  results  will  be  obtained  by  making 
synthetical  assays  and  following  the  methods  here  de- 
scribed, and  the  student  will  find  that  by  adopting  the 
same  he  can  easily  make  his  assays,  check  them  himself , 
and  have  perfect  confidence  in  the  results  he  obtains. 

Synthetical  assays  entail  more  labour  and  time  than 
that  of  using  tables  which  have  been  compiled  by  authorities 
on  the  subject;  but  it  ensures  great  accuracy,  owing  in  a 
great  measure  to  the  different  ways  in  which  different 
operators  use  the  blowpipe,  also  to  the  degrees  of  heat, 
apparatus,  quality  of  material,  and  the  fuel,  &c.,  employed. 

The  following  tables,  with  full  instructions  for  their  use, 
have  been  compiled  by  David  Forbes,  and  will  be  found  of 
great  service  to  the  assay er.1 

'  Determination  of  the  Weight  of  the  Silver  Globule  ob- 
tained on  Cupellation. — As  the  amount  of  lead  which  can, 
by  the  method  before  described,  be  conveniently  cupelled 
before  the  blowpipe  is  necessarily  limited,  the  silver 
globule  which  remains  upon  the  bone-ash  surface  of  the 
cupel  at  the  end  of  the  operation  is,  when  substances  poor 
in  silver  have  been  examined,  frequently  so  very  minute 
that  its  weight  could  not  be  determined  with  correctness 
by  the  most  delicate  balances  in  general  use.' 

The  blowpipe  balance  employed  by  the  author  turns 
readily  with  y^Vo  °^  a  gram?  but  could  not  be  used  for 
•  determining  weights  below  that  amount. 

Grlobules  of  silver  of  far  less  weight  than  1 0iQO  are 
distinctly  visible  to  the  naked  eye — a  circumstance  which 
induced  Harkort  to  invent  a  volumetrical  scale  based 
upon  the  measurement  of  the  diameters  of  the  glo- 

1  See  Mitchell's  Manual  of  Practical  Assaying,  pp.   676-681 ;  also 
D.  Forbes,  Chemical  News,  Nos.  380,  384,  392,  396,  398,  and  412. 


ICQ—  r 

98' 
96- 
94' 
92- 
90- 


ASSAY  OF  SILVER,   GOLD,  ETC.       PART  III. 

bules,  which  scale  in  practice  has  been  found 
of  very  great  utility  in  the  blowpipe  assay 
of  silver. 

The  scale  for  this  purpose  which  is  em- 
ployed by  the  author  is  shown  in  full  size  in 
the  annexed  woodcut. 

This  figure  (5 8)  represents  a  small  strip  of 
highly  polished  ivory  about  6^  inches  long, 
f  inch  broad,  and  |-  inch  in  thickness,  on 
which  are  drawn,  by  an  extremely  fine  point, 
two  very  fine  and  distinct  lines  emanating 
from  the  lower  or  zero  point,  and  diverging 
upwards  until,  at  the  distance  of  exactly  6 
English  standard  inches,  they  are  precisely 
To~o  Parts  °f  an  inch  apart.  This  dis- 
tance (6  inches)  is,  as  shown  in  wood- 
cut, divided  into  100  equal  parts  by  cross 
lines  numbered  in  accordance  from  zero  up- 
wards. It  is  now  evident,  if  a  small  globule 
of  silver  be  placed  in  the  space  between 
these  two  lines,  using  a  magnifying  glass 
to  assist  the  eye  in  moving  it  up  or  down 
until  the  diameter  of  globule  is  exactly  con- 
tained within  the  lines  themselves,  that  we 
have  at  once  a  means  of  estimating  the  dia- 
meter of  the  globule  itself,  and  therefrom  are 
enabled  to  calculate  its  weight. 

As  the  silver  globules  which  cool  upon 
the  surface  of  the  bone-ash  cupel  are  not 
true  spheres,  but  are  considerably  flattened 
on  the  lower  surface,  where  they  touch  and 
rest  upon  the  cupel,  it  follows  that  the  weight 
of  globules  corresponding  in  diameter  to  the 
extent  of  divergence  at  the  different  degrees 
of  the  scale  cannot  be  calculated  directly 


PART  III.  SILVER.  1 1 1 

from  their  diameters  as  spheres,  but  require  to  have 
their  actual  weight  experimentally  determined  in  the  same 
manner  as  employed  by  Plattner. 

The  table  appended  on  next  page  has  been  calculated  by 
the  author,  and  in  one  column  shows  the  diameter  in  English 
inches  corresponding  to  each  number  or  degree  of  the  scale 
itself,  and  in  the  two  next  columns  the  respective  weights 
of  the  flattened  spheres  which  correspond  to  each  degree 
or  diameter ;  for  convenience  these  weights  are  given  in 
the  different  columns  in  decimals,  both  of  English  grains 
and  of  French  grammes. 

These  weights  are  calculated  from  the  following  data, 
found  as  the  average  result  of  several  very  careful  and 
closely  approximating  assays,  which  showed  that  globules  of 
silver  exactly  corresponding  to  No.  95  on  this  scale,  or 
O038  inch  in  diameter,  possessed  a  weight  of  0*0475573 
grain,  or  0*003079  gramme.  From  this  the  respective 
weights  of  all  the  other  numbers  or  degrees  on  this  scale 
were  calculated,  on  the  principle  that  solids  were  to  one 
another  in  the  ratio  of  the  cubes  of  their  diameters. 
This  mode  of  calculation  is  not,  however, absolutely  correct 
in  principle,  for  the  amount  of  flattening  of  the  under  sur- 
face of  the  globule  diminishes  in  reality  with  the  decreasing 
volume  of  the  globule.  In  actual  practice,  however,  this 
difference  may  be  assumed  to  be  so  small  that  it  may  be 
neglected  without  injury  to  the  correctness  of  the  results. 

The  smaller  the  diameter  of  the  globule,  the  less  will 
be  the  difference  or  variation  in  weight  in  descending  the 
degrees  of  this  scale,  since  the  globules  themselves  vary  in 
weight  with  the  cubes  of  their  diameters ;  for  this  reason, 
also,  all  such  globules  as  come  within  the  scope  of  the 
balance  employed  should  be  weighed  in  preference  to 
being  measured,  and  this  scale  should  be  regarded  as  more 
specially  applicable  to  the  smaller  globules  beyond  the 
reach  of  the  balance. 


J  1 2      ASSAY   OF  SILVER,    GOLD,  MERCUEY,   ETC.      PART  III. 


No.  on  Scale 

Greatest  Diame- 
ter in  Inches 

Weight  of  Globule 
in  Grains 

Weight  of  Globule 
in  Grammes 

1 

0-0004 

0-00000005 

0-000000003 

2 

0-0008 

0-00000044 

0-000000028 

3 

0-0012 

0-00000149 

0-000000090 

4 

o-ooio 

0-00000355 

0-000000229 

5 

0-0020 

0-0000009 

0-00000044 

6 

0-0024 

0-0000119 

0-00000077 

7 

0-0028 

0-0000190 

0-00000120 

8 

0-0032 

0-0000284 

0-00000184 

9 

0-0030 

0-0000403 

0-00000202 

10 

0-0040 

0-0000554 

0-00000359 

11 

0-0044 

0-0000730 

0-00000478 

12 

0-0048 

0-0000958 

0-00000020 

13 

0-0052 

0-0001218 

0-00000789 

14 

0-0050 

0-0003522 

0-00000985 

15 

o-ooeo 

0-0001872 

0-00001203 

10 

0-0004 

0-0002272 

0-00001471 

17 

0-0008 

0-0002725 

0-00001704 

18 

0-0072 

0-0003234 

0-00002094 

19 

0-0070 

0-0003804 

0-00002403 

20 

0-0080 

0-0004437 

0-00002872 

21 

0-0084 

0-0005137 

0-00003327 

22 

0-0088 

0-0005900 

0-00003823 

23 

0-0092 

0-0000748 

0-00004307 

24 

0-0090 

0-0007008 

0-00004904 

25 

o-oioo 

0-0008007 

0-00005011 

20 

0-0104 

0-0009749 

0-00000311 

27 

0-0108 

0-0010918 

0-00007008 

28 

0-0112 

0-0012170 

0-00007883 

29 

o-oiio 

0-0013528 

0-00008758 

30 

0-0120 

0-0014970 

0-00009090 

31 

0-0124 

0-0010524 

0-00010098 

32 

0-0128 

0-0018170 

0-00011077 

33 

0-0132 

0-0019934 

0-00012817 

34 

0-0130       0-0021801 

0-00014114 

35 

0-0140 

0-0023780 

0-00015397 

30 

0-0144 

0-0025879 

0-00010755 

37 

0-0148 

0-0028097 

0-00018190 

38 

0-0152 

0-0030437 

0-00019705 

39 

0-0150 

0-0032903 

0-00021302 

40 

o-oioo 

0-0035550 

0-00022983 

41 

0-0104 

0-0038230 

0-00024751 

42 

0-0108 

0-0041090 

0-00020000 

43 

0-0172 

0-0044111 

0-00028553 

44 

0-0170 

0-0047250 

0-00030589 

PART  III. 


SILVER, 


113 


No.  on  Scale 

Greatest  Diameter 
in  Inches 

Weight  of  Globule 
in  Grains 

Weight  of  Globule 
in  Grammes 

45 

0-0180 

0-0050546 

0-00032725 

46 

0-0184 

0-0053991 

0-00034955 

47 

0-0188 

0-0057590 

0-00037285 

48 

0-0192 

0-0061344 

0-00039716 

49 

0-0196 

0-0065258 

0-00042250 

50 

0-0200 

0-0069335 

0-00044890 

51 

0-0204 

0-0073581 

0-00047638 

52 

0-0208 

0-0077799 

0-00050495 

53 

0-0212 

0-0082580 

0-00053464 

54 

0-0216 

0-00873438 

0-00056549 

55 

0-0220 

0-00922854 

0-00059748 

56 

0-0224 

0-0097412 

0-00063067 

57 

0-0228 

0-0102725 

0-00066506 

58 

0-0232 

0-0108228 

0-00070021 

59 

0-0236 

0-0113922 

0-00073753 

60 

0-0240 

0-0119815 

0-00077570 

61 

0-0244 

0-0125901 

0-00081513 

62 

0-0248 

0-0132119 

0-00085588 

63 

0-0252 

0-0138901 

0-00089797 

64 

0-0256 

0-0145440 

0-00094141 

65 

0-0260 

0-0152311 

0-00098623 

66 

0-0264 

0-0159472 

0-00103245 

67 

0-0268 

0-0166828 

0-00108010 

68 

0-0272 

0-0174414 

0-00112918 

69 

0-0276 

0-0182220 

0-00117974 

70 

0-0280 

0-0190256 

0-00123177 

71 

0-0284 

0-0198529 

0-00128535 

72 

0-0288 

0-0207035 

0-00134041 

73 

0-0292 

0-0215782 

0-00139704 

74 

0-0296 

0-0224469 

0-00145525 

75 

0-0300 

0-0234010 

0-00151504 

76 

0-0304 

0-0243496  ' 

0-00157645 

77 

0-0308 

0-0253224 

0-00163950 

78 

0-0312 

0-0263228 

0-00170422 

79 

0-0316 

0-0273484 

0-00177060 

80 

0-0320 

0-0284000 

0-00183869 

81 

0-0324 

0-0294789 

0-00190852 

82 

0-0328 

0-0305838 

0-00198008 

83 

0-0332 

0-0317162 

0-00205340 

84 

0-0336 

0-0328768 

0-00212851 

85 

0-0340 

0-0340649 

0-00220549 

86 

0-0344 

0-0349739 

0-00228400 

87 

0-0348 

0-0364422 

0-00235938 

88 

0-0352 

0-0378008 

0-00244730 

114      ASSAY   OF  SILVEE,   GOLD,   MERCUKY,   ETC.      PART  III. 


No.  on  Scale 

Greatest  Diameter 
in  Inches 

Weight  of  G-lobule 
in  Grains 

Weight  of  Globule 
in  Grammes 

89 

0-0356 

0-0390138 

0-00253168 

90 

0-0360 

0-0404368 

0-00261797 

91 

0-0364 

0-0417943 

0-00270790 

92 

0-0368 

0-0431930 

0-00279642 

93 

0-0372 

0-0446162 

0-00288860 

94 

0-0376 

0-0460718 

0-00298279 

95 

0-0380 

0-0475573 

0-00307900 

96 

0-0384 

0-0465239 

0-00317728 

97 

0-0388 

0-0506249 

0-00327759 

98 

0-0392 

0-0522069 

0-00338020 

99 

0-0396 

0-0538215 

0-00348452 

100 

0-0400 

0-0554688 

0-00359138 

Silver  Assay.  Cupellation  Loss. — This  term  is  ap- 
plied to  indicate  a  minute  loss  of  silver,  unavoidably 
sustained  in  the  process  of  cupellation,  which  arises  from  a 
small  portion  of  that  metal  being  mechanically  carried 
along  with  the  litharge  into  the  body  of  the  cupel.  The 
amount  of  this  loss  increases  with  the  quantity  of  lead 
present  in  the  assay  (whether  contained  originally  in  the 
assay  or  added  subsequently  for  the  purpose  of  slagging  off 
the  copper,  &c.);  it  is  relatively  greater,  as  the  silver 
globule  is  larger,  but  represents  a  larger  percentage  of  the 
silver  actually  contained  in  the  assay,  in  proportion  as  the 
silver  globule  obtained  diminishes  in  size.  It  has,  however, 
been  experimentally  proved  that  in  assays  of  like  richness 
in  silver,  this  loss  remains  constant  when  the  same 
temperature  has  been  employed,  and  similar  weights  of 
lead  been  oxidised  in  the  operation. 

In  the  blowpipe  assay  this  loss  is  not  confined  to  the 
ultimate  operation  of  cupellation,  but  occurs,  though  in  a 
less  degree,  in  the  concentration  of  the  silver  lead,  and  in 
the  previous  scorification  of  the  assay,  had  such  operation 
preceded  the  concentration.  The  total  loss  in  the  blow- 
pipe assay  is  found,  however,  to  be  less  than  in  the  ordinary 


PART  III. 


SILVER. 


115 


muffle  assay,  since  in  the  latter  case  the  whole  of  the 
oxidised  lead  is  directly  absorbed  by  the  cupel. 

In  mercantile  assays  of  ore  it  is  not  customary  to  pay 
attention  to  the  cupellation  loss,  and  the  results  are  usually 
stated  in  the  weight  of  silver  actually  obtained.  Where, 
however,  great  accuracy  is  required,  especially  when  the 
substances  are  very  rich  in  silver,  the  cupellation  loss  is 
added  to  the  weight  of  the  silver  globule  obtained,  in  order 
to  arrive  at  the  true  percentage. 

The  amount  to  be  added  for  this  purpose  is  shown  in 
the  annexed  table,  which  is  slightly  modified  from  Platt- 


ner  s : — 


Actual  Per- 
centage of 
Silver  found 
by  Assay 

Cupellation  Loss,  or  Percentage  of  Silver  to  be  added  to  the  actual  per- 
centage found  by  assay  in  order  to  show  the  true  percentage  of  silver 
contained  in  same,  the  entire  amount  of  lead  in  or  added  to  the  assay 
being  the  following  multiples  of  the  original  weight  of  assay  :— 

1 

2 

3 

4 

5 

6 

8 

11 

13 

16 

99-75, 
99-5   / 

0-25 

0-32 

0-39 

0-45 

0-50 

— 

— 

— 

— 

— 

90 

0-22 

0-29 

0-36 

0-42 

0-47 

0-69 

0-83 

— 

— 

— 

80 

0-20 

0-26 

0-33 

0-3^ 

0-44 

0-64 

0-75 

— 

— 

— 

70 

0-18 

0-23 

0-29 

0-35 

0-40 

0-58 

0-68 

0-82 

— 

— 

60 

0-16 

0-20 

0-26 

0-30 

0-36 

052 

0-61 

0-74 

— 

— 

50 

0'14 

0-17 

0-23 

0-26 

0-32 

0-46 

0-54 

0-65 

— 

— 

40 

0-12 

0-15 

020 

0-22 

0-27 

0-39 

0-46 

0-55 

0-62 

— 

35 

0-11 

0-13 

0-18 

0-18 

0-25 

0-36 

0-42 

0-50 

0-57 

— 

30 

o-io 

012 

0-16 

016 

0-22 

0-32 

0-38 

0-45 

0-51 

— 

25 

0-09 

o-io 

0-14 

0-14 

0-20 

0-29 

0-34 

0-40 

0-45 

— 

20 

0-08 

0-09 

0-12 

012 

0'17 

0-25 

0-29 

0-35 

0-39 

0-45 

15 

0-07 

0-08 

o-io 

O'll 

0-15 

0-20 

0-23 

0-28 

0-32 

0-37 

112 

0-06 

0-07 

0-09 

o-io 

0-13 

0-17 

0-19 

0-23 

0-26 

0-32 

10 

0-05 

0-06 

0-08 

0-09 

0-11 

0-15 

0-17 

0-20 

0-23 

0-27 

!    9 

0-04 

0-05 

0-07 

0-08 

o-io 

0-14 

0-16 

0-18 

0-21 

0-25 

!    8 

0-03 

0-04 

0-06 

0-07 

0-09 

0-13 

0-15 

0-16 

0-18 

0-22 

!    7 

0-02 

0-03 

0-05 

0-06 

0-08 

0-12 

0-13 

0'14 

0-16 

0-20 

6 

o-oi 

0-02 

0-04 

0-05 

0-07 

o-io 

O'l] 

0-12 

014 

0-17 

5 



o-oi 

0-03 

0-04 

0-06 

0-09 

o-io 

O'll 

0-12 

0-14 

4 



— 

0-02 

0'03 

0-05 

0-07 

0-08 

0-09 

o-io 

0-11 

3 

— 



o-oi 

0-02 

0-04 

0-05 

0-06 

0-07 

0-08 

0-09 

2 







o-oi 

0-03 

0-04 

0-04 

0-05 

0-06 

0-07 

1 

— 

— 

— 

— 

o-oi 

0-03 

0-03 

0-04 

0-04 

005 

116      ASSAY   OF  SILVER,   GOLD,   MERCURY,   ETC.      PART  III. 

The  use  of  the  above  table  is  best  explained  by  an 
example,  as  the  following  :  — An  assay  to  which  there  had 
been  added,  in  all,  five  times  its  weight  of  assay  lead,  gave 
a  globule  of  silver  equivalent  to  6  per  cent.  Upon  refer- 
ring to  the  table,  it  will  be  seen  that  the  cupellation  loss 
for  this  would  be  0'07  ;  consequently  the  true  percentage 
of  silver  contained  in  the  assay  would  be  6*07.  This  table 
is  only  extended  to  whole  numbers,  but  fractional  parts 
can  easily  be  calculated  from  the  same. 

To  enable  the  operator  to  sum  up  the  result  of  his  assays 
the  author  has  compiled  the  following  tables  for  estimating 
the  amount  of  gold  or  silver  in  one  ton  of  ore,  also  the  per- 
centage found  in  the  'assay  sample'  of  1  j  grain. 

They  are  arranged  for  both  the  '  long '  and  '  short ' 
ton,  and  have  been  calculated  from  the  following  data  : — 

Avoirdupois. 

4  Long  ton'        .  =20cwt.    =  2,240  Ibs.      =1015 '649    kilogrammes. 
<  Short  ton'       .         .         .=2,000,,         =   906'8296  „ 

Hundredweight         .         .  =     112  „         =     50 '78245  ,, 

Quarter    .         .         .         .=       28,,         =     12  -6956144  kilogrms. 
Pound      .         .=16oz.      =7,000  grains  =   433'4148    grammes. 
Ounce       .         .  =16  drams  =    437 '5  ,,     =     28 '3375  „ 

Dram        .         .         .         .=       27 '344     =       1  "77108  gramme. 

Troy  (Precious  Metals}. 

Pound      .         .=12oz.      =5,760  grains  =   373 '096        grammes. 
Ounce      .         .  =20dwt.  =     480       „     =      31 '0913  „ 

Pennyweight    .       ..         .=       24       ,,     =        1  '55457    gramme. 
Grain        .         .         .         .         .         .  0'064773         ,, 

Owing  to  the  great  fluctuation  which  has  of  late  years 
taken  place  in  the  value  of  silver  no  permanent  standard  can 
be  made  for  its  value  per  ounce,  and  the  assayer  should  re- 
port only  the  ounces  or  percentage  found,  and  give  the 
market  value  to  date  of  same. 

After  the  weight  of  the  silver  has  been  determined  the  but- 
ton must  always  be  examined  to  see  if  it  contains  any  gold  (by 
dissolving  it  in  nitric  acid),  and  if  such  is  found  the  weight 
of  same  must  be  ascertained  and  deducted  from  that  of  the 
button,  and  the  percentage  of  silver  estimated  accordingly. 


PART  III. 


SILVER. 


117 


Gold  and  Silver  Tables  for  calculating  the  amount  of  gold 
or  silver  in  1  ton  of  2,240  Ibs.,  or  35,840  ounces,  or 
15,680,000  grains,  using  1^  grain  for  the  assay  sample. 


Weight  of 
Ore  or  Alloy. 
Grains 

Gave  Fine  Metal. 
Grains 

Equivalent  per  Ton  to 
Ounces    Dec. 

Equivalent  to 
per  Cent. 

1-5 

1-000000 

23893-33 

66-666 

1-5 

0-900000 

21503-99 

59-999 

1-5 

0-800000 

19114-66 

53-333 

1-5 

O'TOOOOO 

16725-33 

46-666 

1-5 

0-600000 

14335-99 

39-999 

1-5 

0-500000 

11946-66 

33-333 

1-5 

0-400000 

9557-33 

26-666 

1-5 

0-300000 

7167-99 

19-999 

1-5 

0-200000 

4778-66 

13-333 

1-5 

o-iooooo 

2389-33 

06-666 

1-5 

0-090000 

2150-39 

-   05-999 

1-5 

0-080000 

1911-46 

05-333 

1-5 

0-070000 

1672-53 

04-666 

1-5 

0-060000 

1433-59 

03-999 

1-5 

0-050000 

1194-66 

03-333 

1-5 

0-040000 

955-73 

02-666 

1-5 

0-030000 

716-79 

01  -999 

1-5 

0-020000 

477-86 

01-333 

1-5 

o-oioooo 

238-93 

00-6666 

1-5 

0-009000 

215-03 

00-5999 

1-5 

0-008000 

191-14 

00-5333 

1-5 

0-007000 

167-25 

00-4666 

1-5 

0-006000 

143-35 

00-3999 

1-5 

0-005000 

119-46 

00-3333 

1-5 

0-004000 

95-57 

00-2666 

1-5 

0-003000 

71-67 

00-1999 

1-5 

0-002000 

47-78 

00-1333 

1-5 

o-ooiooo 

23-89 

00-06666 

1-5 

0-000900 

21-50 

00-05999 

1-5 

0-000800 

19-11 

00-05333 

1-5 

0-000700 

16-72 

00-04666 

1-5 

0-000600 

14-33 

00-03999 

1-5 

0-000500 

11-94 

00-03333 

-    1-5 

0-000400 

9-55 

00-02666 

1-5 

0-000300 

7-16 

00-01999 

1-5 

0-000200 

.  4-77 

00-01333 

1-5' 

o-oooioo 

2-38 

00-006666 

1-5 

0-000090 

2-15 

00-005999 

1-5 

0-000080 

1-91 

00-005333 

118      ASSAY   OF  SILVER,   GOLD,  MERCURY,  ETC.      PART  III. 


Gold  and  Silver  Tables — continued. 


Weight  of 
Ore  or  Alloy. 
Grains 

Gave  Fine  Metal. 
Grains 

Equivalent  per  Ton  to 
Ounces     Dec. 

Equivalent  to 
per  Cent. 

1-5 

0-000070 

1-67 

00-004666 

1-5 

0-000060 

1-43 

00-003999 

1-5 

0-000050 

1-19 

00-003333 

1-5 

0-000040 

0-95 

00-002666 

1-5 

0-000030 

0-71 

00-001999 

1-5 

0-000020 

0-47 

00-001333 

1-5 

o-ooooio 

0-23 

00-0006666 

1-5 

0-000009 

0-215 

00-0005999 

1-5 

0-000008 

0-191 

00-0005333 

1-5 

0-000007 

0-167 

00-0004666 

1-5 

0-000006 

0-143 

00-0003999 

1-5 

0-000005 

0-119 

00-0003333 

1-5 

0-000004 

0-095 

00-0002666 

1-5 

0-000003 

0-071 

00-0001999 

1-5 

0-000002 

0-047 

00-0001333 

1-5 

o-oooooi 

0-023 

00-00006666 

Gold  and  Silver  Tables  for  calculating  the  amount  of  gold 
or  silver  in  1  ton  of  2,000  Ibs.,  or  32,000  ounces,  or 
14,000,000  grains,  using  1^  grain  for  the  assay  sample. 


Weight  of 
Ore  or  Alloy. 
Grains 

Gave  Fine  Metal. 
Grains 

Equivalent  per  Ton  to 
Ounces     Dec. 

Equivalent  to 
per  Cent. 

1.5 

i-oooooo 

21333-33 

66-666 

1-5 

0-900000 

19200-00 

59-999 

1-5 

0-800000 

17066-66 

53-333 

1-5 

0-700000 

14933-22 

46-666 

15 

0-600000 

12799-99 

39-999 

1-5 

0-500000 

10666-66 

33-333 

1-5 

0-400000 

8533-33 

26-666 

1-5 

0-300000 

6399-99 

19-999 

1-5 

0-200000 

4266-66 

13-333 

1-5 

o-iooooo 

2133-33 

06-666 

1-5 

0-090000 

.      1920-00 

05-999 

1-5 

0-080000 

1706-66 

05-333 

1-5 

0-070000 

1493-32 

04-666 

1-5 

0-060000 

1279-99 

03-999 

1-5 

0-050000 

1066-66 

03-333 

1-5 

0-040000 

853-33 

02-666 

PART  III.  SILVER. 

Gold  and  Silver  Tables — continued. 


119 


Weight  of 
Ore  or  Alloy. 
Grains 

Gave  Pine  Metal. 
Grains 

Equivalent  per  Ton  to 
Ounces  Dec. 

Equivalent  to 
per  Cent. 

1-5 

0-030000 

639-99 

01-999 

1*6 

0-020000 

426-66 

01-333 

1-5 

o-oioooo 

213-33 

00-6666 

1-5 

0-009000 

192-00 

00-5999 

1-5 

0-008000 

170-66 

00-5333 

1-5 

0-007000 

149-33 

00-4666 

1-5 

0-006000 

127-99 

00-3999 

1-5 

0-005000 

106-66 

00-3333 

1-5 

0-004000 

85-33 

00-2666 

1-5 

0-003000 

63-99 

00-1999 

1*6 

0-002000 

42-66 

00-1333 

1-5 

o-ooiooo 

21-33 

00-06666 

1-5 

0-000900 

19-20 

00-05999 

1-5 

0-000800 

17-06 

00-05333 

1-5 

0-000700 

14-93 

00-04666 

1-5 

0-000600 

12-79 

00-03999 

1-5 

0-000500 

10-66 

00-03333 

I'd 

0-000400 

8-53 

00-02666 

1-5 

0-000300 

6-39 

00-01999 

1-5 

0-000200 

4-26 

00-01333 

1-5 

o-oooioo 

2-13 

00-006666 

1*5 

0-000090 

1-92 

00-005999 

1-5 

0-000080 

1-70 

00-005333 

1-5 

0-000070 

1-49 

00-004666 

1-5 

0-000060 

1-27 

00-003999 

1-5 

0-000050 

1-06 

00-003333 

1-5 

0-000040 

0-85 

00-002666 

1-5 

0-000030 

0-63 

00-001999 

1-5 

0-000020 

0-42 

00-001333 

1-5 

o-ooooio 

0-21 

00-0006666 

1-5 

0-000009 

0-192 

00-0005999 

1-5 

0-000008 

0-170 

000005333 

1-5 

0-000007 

0-149 

00-0004666 

1-5 

0-000006 

0-127 

00-0003999 

1-5 

0-000005 

0-106 

00-0003333 

1-5 

0-000004 

0-085 

00-0002666 

1-5 

0-000003 

0-063 

00-0001999 

1*6 

0-000002 

0-042 

00-0001333 

1-5 

o-oooooi 

0-021 

00-00006666 

Class  A  (b). — This  class  consists  only  of  argentiferous  mo- 
lybdenite, and  decomposes  very  readily  when  soda  is  used. 


120      ASSAY    OF  SILVER,   GOLD,   MERCURY,   ETC.      PART  III. 

The  ore  is  finely  powdered,  and  1-5  grain  is  fluxed  with 
7 '5  grains  proof  lead,  2-3  soda,  and  2 -3  borax  glass  in  a 
soda-paper  cornet  (which  has  been  previously  placed  in 
a  charcoal  bore),  and  is  heated  with  a  strong  E.F. 
When  the  assay  is  thoroughly  fused  incline  it  gently 
and  allow  the  lead  globules  to  come  out  from  under  the 
slag.  Treat  it  with  the  O.F.  for  several  minutes,  until  all 
the  molybdenum  is  volatilised ;  then  allow  it  to  cool,  and 
scorify  and  cupel  as  before. 

Class  A  (c). — To  this  class  belong  bromyrite,  cerar- 
gyrite,  embolite,  iodyrite,  all  ores  and  furnace  products 
calcined  with  salt,  amalgamation  residues,  old  test  and 
cupels,  all  argentiferous  slags,  and  silver  sweeps  and 
polishings. 

Finely  powdered  ore  .         .         .     1'5  grain. 
Borax  glass      '  .  -       .         .   .      .     I'O      ,, 
Proof  lead          t        *.         .         .     7 '5  grains. 

The  above,  after  being  mixed,  is  placed  in  a  soda- 
paper  cornet  on  charcoal,  and  fused  by  a  R.F.  until  all 
the  silver  is  combined  with  the  lead,  and  the  slag  shows 
itself  as  a  perfectly  fluid  globule.  If  copper  is  present- 
in  the  ore  the  quantity  of  assay  lead  must  be  added 
in  proportion  to  the  percentage  of  copper,  as  stated 
under  A  (a). 

Taking  all  the  precautions  noted  under  reduction  of 
Glass  A  (a),  the  assay  is  soon  finished,  as  the  chlorine, 
bromine,  and  iodine  unite  and  form  chlorides,  bromides, 
and  iodides  of  lead,  which  volatilise,  whilst  the  silver 
unites  with  the  lead. 

The  reduced  lead  is  scorified  and  cupelled,  as  described 
in  Class  A  (a). 

Class  A  (d). — The  most  important  substance  of  this 
class  is  litharge  (lead  oxide),  which  is  readily  reduced  on 
charcoal,  but  generally  very  poor  in  silver ;  so  it  is  neces- 


PART  III.  SILVER,  121 

sary  to  take  a  larger  amount  for  assay  than  is  ordinarily 
used. 

Five  times  the  weight  of  the  usual  assay  sample — 7'5 
grains — is  mixed  with  1  grain  borax  glass  and  1  grain  soda 
in  a  soda-paper  cornet,  and  treated  with  R.F.  until  all  the 
oxide  is  reduced  and  the  fluid  slag  shows  no  lead  globules. 
Towards  the  end  of  the  operation  the  flame  is  directed 
principally  on  to  the  slag ;  otherwise  the  metal  may 
become  too  much  agitated  and  cause  a  loss.  The  silver 
lead  thus  obtained  is  then  ready  for  scorification  and 
cupellation,  and  it  can  be  proceeded  with  as  described  in 
Class  A  (a). 

N.E.  It  is  often  found  necessary  to  make  several  assays 
of  substances  of  the  above  class,  on  account  of  the  very 
small  amount  of  silver  they  contain. 

Class  A  (e). — General  method  adapted  to  the  assay  of 
a,  by  c,  either  to  one  or  all  (d,  being  composed  of  litharge, 
does  not  come  under  the  head  of  this  assay). 

Take  finely  powdered  ore  1/5  grain,  and  add  to  it 
from  five  to  ten  times  its  FIQ  59  (Fullsize0 

weight  in  finely  powdered 
litharge  (which  must  be 
free  from  silver).  The 
excess  of  litharge  is  neces- 
sary only  when  the  ore  con- 
tains a  large  amount  of 
metallic  sulphides  ;  for  ordinary  ores  5  times  the  weight 
will  be  found  ample.  Add  soda  0-7  grain  and  finely 
powdered  charcoal  0-5  grain. 

Mix  intimately  and  then  remove  to  a  small  fire-clay 
crucible  (see  fig.  59). 

A  piece  of  platinum  wire  is  now  bent  into  the  required 
form  to  act  as  a  holder  and  support  to  the  crucible  whilst 
it  is  in  the  charcoal  furnace  (see  fig.  60). 


FIG.  60.  (Full  size.) 


.122      ASSAY   OF   SILVER,   GOLD,   MERCUEY,   ETC.      PART  III. 

The  charcoal  furnace  (fig.  61)  is  made  out  of  two  sound 
pieces  of  charcoal,  and  the  inside  bored  out  by  the  large 

borer  (see  fig.  28,  appara- 
tus), and  the  blast  hole  and 
escape  way  made  by  the  small 
borer  (see  fig.  30,  apparatus). 
For  furnace  holder  see  Mer- 
cury Assay. 

The  crucible,  already 
charged,  is  placed  in  the  fur- 
nace and  held  in  its  place  by 
the  platinum  wire.  The  fur- 
nace is  then  held  securely  by 
the  holder;  the  flame  is 
applied  through  the  blast 
hole — at  first  a  gentle  flame, 
then  a  strong  E.F.  Flames 
will  soon  be  seen  to  issue  from  the  top  hole,  and  by 
looking  into  the  same  the  operator  can  see  whether  the 
assay  is  fused  or  not.  If  it  is  found  to  be  fused,  give  it  a 
strong  blast  for  about  one  minute,  and  then  allow  it  to 
cool.  The  crucible,  when  cool,  is  broken  and  the  lead 
button  cleaned.  The  slag  must  be  examined,  and  if  a  per- 
fect fusion  has  not  taken  place  the  assay  must  be  repeated. 
The  assay  will  be  finished  as  described  in  a. 

Class  B  (a)  consists  of  alloys  ready  for  cupellation 
after  an  addition  of  lead.  The  following  table  will  guide 
the  operator  in  regard  to  the  quantity  of  lead  required. 

The  sample  to  be  assayed  is  either  hammered  or  rolled 
out,  and  from  1  to  2  grains  weighed  for  assay. 

A  preliminary  assay  should  first  be  made  and  an  ex- 
cess of  lead  added.  After  cupelling  and  ascertaining  the 
approximate  fineness,  the  assay  can  be  prepared  according 
to  the  following  scale,  and  the  synthetical  also. 


PART  III. 


SILVER. 


123 


Table  of  the  Amount  of  Test  Lead  to  be  added  to  Alloys  of 
Copper  and  Silver  for  their  Cupellation  by  the  Blowpipe. 


FiiienesH  of 
Silver 

Parts  of 
Lead 

t  ineness  of 
Slver 

Parts  of 
Lead 

1000 

2 

750 

11 

975 

4 

700 

12 

950 

5 

650 

13 

925 

6 

600 

14 

900 

7 

550 

15 

875 

8 

500 

16 

850 

9 

100 

17 

800 

10 

Take  from  1  to  2  grains  of  the  alloy,  and,  after 
adding  the  amount  of  lead  necessary,  place  it  on  a  pre- 
viously prepared  cupel  and  proceed  according  to  method 
described  in  p.  106  under  the  head  of  '  Cupellation.' 

The  synthetical  assay  is  conducted  in  the  same  manner, 
and  its  loss  of  silver  should  be  added  to  what  is  found  in 
the  assay  of  the  alloy,  which  will  give  the  actual  loss  ex- 
perienced in  the  manipulation.  The  button  obtained  from 
the  alloy  must,  after  weighing,  be  always  tested  for  gold 
by  dissolving  it  in  nitric  acid,  and  if  gold  is  present  the 
weight  of  the  same  is  deducted  from  that  of  the  silver. 

In  assaying  silver  bars  that  are  over  950  fine  it  is 
advisable  not  to  take  more  than  1  grain  for  assay,  and  in 
all  cases  where  the  operator  has  not  had  much  practice  it  is 
best  to  only  take  1  grain. 

Class  C  (a),  consisting  of  amalgams,  is  treated  first 
according  to  assay  of  mercury  and  Class  (7,  p.  137.  The 
retorted  residue  is  now  assayed  according  to  6. 

(6)  Two  grains  of  the  precipitated,  or  retorted,  silver 
are  fused  on  charcoal  with  0*7  grain  of  borax,  and  the 
button  thus  cleaned  is  cupelled  as  an  alloy.  See  Class  B  (a). 

(c)  Consisting  of  brass,  black  copper. 

Take  of  alloy  1  grain  and  mix  with  15  times  its  weight 


124      ASSAY   OF    SILYEE,   GOLD,   MEECUEY,   ETC.      PART  III. 

of  lead  and  1  grain  of  borax  glass ;  melt  with  a  strong 
R.F.  until  a  complete  fusion  has  taken  place  and  the  silver 
lead  button  has  a  bright  appearance.  Then  scorify  and 
cupel  according  to  Class  A  (a). 

(c£)  Tin  and  gun  metal. 

Fuse  1  grain  of  the  alloy  with  12  parts  assay  lead  and 
0-5  grain  dry  carbonate  of  soda  and  0'5  grain  borax  glass. 
Place  in  a  soda  cornet  and  fuse  in  charcoal.  First  apply  a 
strong  E.F.  As  soon  as  the  assay  is  melted,  change  the 
flame  to  an  oxidising  one,  and  continue  until  all  the  tin  has 
become  absorbed  in  the  flux. 

If  any  tin  is  suspected  to  be  still  in  the  alloy,  remove 
the  button  and  again  scorify  with  a  little  borax  on  char- 
coal, as  tin  cannot  be  cupelled.  The  button  should  now  be 
treated  as  Class  A  (a). 

(e)  Antimony,  tellurium,  and  zinc. 

One  grain  of  the  alloy  is  mixed  with  5  grains  lead 
and  O5  grain  borax  glass,  and  melted  on  a  soda  cornet  on 
charcoal.  A  strong  R.F.  is  first  applied,  then  an  O.F., 
until  the  lead  button  appears  clear  and  white.  If  the 
latter  does  not  occur  in  a  few  minutes  allow  the  assay  to 
cool,  and  repeat  the  fusion  with  more  lead  and  borax  until 
it  does.  Then  finish  as  in  A  (a). 

(/)  Silver-steel  and  iron  not  uniting  with  lead,  the 
alloy  must  be  first  converted  into  a  sulphide  of  iron  by 
fusion  with  sulphur. 

The  alloy  must  be  broken  into  fragments,  the  largest 
not  to  weigh  over  0'5  grain. 

Take  1  '5  grain   alloy  fragments. 
, ,  12'0  grains  lead. 
,,     1*0  grain   borax  glass. 
,,     0'8       ,,     sulphur. 

Fuse  in  a  soda-paper  cornet  on  charcoal  with  the  R.F. 
until  a  good  fluid  globule  is  formed,  then  add  1-5  grain 


TAUT  III.  SILVER.  125 

more  borax  glass  to  complete  the  slagging  of  the  iron. 
Treat  with  a  strong  O.F.  until  the  lead  is  clear  and  has 
a  bright  surface.  Then  cool,  clean,  and  treat  as  in  A  (a). 

((/)  Alloys  of  lead  or  bismuth. 

Take  10  grains  and  melt  with  a  little  borax  on  char- 
coal. Then  clean  the  button,  and  if  it  is  found  brittle 
(from  an  excess  of  bismuth)  add  a  small  quantity  of  lead 
and  then  scorify  and  cupel.  See  A  (a). 

(Ji)  Copper  coins,  wire,  and  cement,  containing  some- 
times nickel. 

Take  1*5  grain  of  the  alloy  and  fuse  with  10  grains 
lead  and  0'7  grain  of  borax  glass  on  charcoal.  When  the 
assay  has  been  fused  apply  the  O.F.,  to  slag  as  much  as 
possible  of  the  copper.  Clean  the  button  when  the  borax 
and  litharge  are  fully  charged  with  the  copper  oxide. 
Then  scorify  with  20  grains  of  lead  and  0'5  grain  of  borax, 
as  in  A  (a),  and  finish  the  assay  as  usual. 

GOLD. 

Grold  is  nearly  ajways  found  in  the  metallic  state,  but 
4  never  pure.'  A  good  crystal  is  considered  a  rarity.  The 
octahedron  and  dodecahedron  are  the  most  common  forms. 
Crystals  sometimes  acicular,  through  elongation  of  octa- 
hedral or  other  forms ;  also  passing  into  filiform,  reticulated, 
and  arborescent  shapes,  and  occasionally  spongiform  from 
an  aggregation  of  filaments  ;  edges  of  crystals  often  salient. 
Cleavage  none.  Twins  :  twinning  plane  octahedral.  Also 
massive  and  in  thin  laminae.  The  above  forms  usually 
occur  in  veins  or  lodes. 

In  alluvial  soils,  streams,  rivers,  and  gravel  beds  gold 
is  generally  found  in  flattened  grains  or  scales  and  in 
rolled  masses. 

Hardness  =  2-5  — 3.  Spec,  gravity  =15-6  — 19*5;  19'30 
—  19*34  when  quite  pure  (Gr.  Kose). 


126      ASSAY   OF  SILVER,   GOLD,   MERCURY,   ETC.      PAKT  III. 

Gold  is  generally  alloyed  with  silver  in  various  propor- 
tions, arid  pieces  from  California,  Idaho,  and  Nevada, 
U.S.A.,  have  been  assayed  by  the  author  and  found  to  con- 
tain as  much  as  50  per  cent,  silver ;  whilst  the  purest  native 
gold  from  the  same  sources  that  he  has  examined  have 
assayed  97  per  cent,  pure  gold  and  nearly  3  per  cent,  silver. 

Gold  is  also  found  combined  with  copper,  iron,  bismuth, 
palladium,  rhodium,  and  tellurium. 

Grold  combines  with  mercury  in  what  is  generally 
termed  gold  amalgam. 

Gold  is  also  found  associated  (or  as  an  incidental  ingre- 
dient) with  certain  ores  containing  iron  and  copper  pyrites, 
mispickel,  blende,  and  galena. 

In  metallurgical  works  the  proportions  of  mercury  to 
gold  in  amalgam  vary  greatly,  owing  to  the  size  as  well  as  the 
purity  of  the  particles  of  gold  which  have  been  brought 
into  contact  with  the  mercury.  The  author  has  found  in 
reduction  works  in  California  that  the  percentage  of 
mercury  in  the  gold  amalgam  there  obtained  varied  from 
36  to  85  per  cent. 

Nearly  all  metallurgical  products  from  lead,  silver,  and 
copper  smelting  works  contain  gold,  and  especially  those 
obtained  from  the  smelting  of  argentiferous  lead  ores ;  but 
as  a  general  rule  the  quantity  is  too  small  to  pay  for  extrac- 
tion, as  in  many  instances  '  a  slight  trace '  can  only  be 
found  by  the  most  careful  analysis. 

Gold  Assay. 

The  assay  for  gold,  although  apparently  easy,  is  de- 
cidedly the  reverse,  and  accurate  results  depend  greatly 
upon  the  judgment  of  the  operator  in  first  selecting  the 
sample  and  then  employing  the  correct  method  of  assaying 
the  same. 

Gold  is  separated  from  its  matrix  by  fusion  with  lead, 
and  the  button  so  obtained  is  scorified  in  the  same  manner 


PART  III.  GOLD.  127 

as  the  ores  described  in  the  silver  assay.  Gold  alloys  are 
fused  with  lead;  three  times  the  weight  of  pure  silver 
is  added,  then  the  assay  is  cupelled  and  the  button  boiled 
in  nitric  acid,  which  dissolves  the  silver,  leaving  the  gold 
in  a  fine  powder,  which  is  heated  to  redness  and  weighed. 

In  assaying  gold  ores  it  is  necessary  to  take  a  large 
quantity  for  assay,  and  as  such  cannot  be  fused  by  the 
blowpipe  the  author  has  adopted  the  following  methods : — 

The  assay  of  gold  is  divided  into  three  classes — A,  B,  C. 

A.  Ores,  minerals,  furnace  slags,  mint,  and  jewellers 
sweeps. 

B.  Gold  alloys. 

C.  Gold  amalgams. 

A  (a).  Ordinary  gold  ores,  from  which  the  metal  is 
extracted  by  raw  amalgamation.  Wash  5  Ibs.  (80  oz.)  in 
a  batea ;  then  collect  the  sulphides,  &c.  (from  which  the 
lighter  portions  have  been  separated  by  the  vanning), 
remove  them  to  a  flask,  and  boil  in  nitric  acid;  then 
filter,  and  burn  the  filter  paper  and  insoluble  residue 
in  a  small  evaporating  dish,  add  twice  its  weight  of  lead 
and  its  own  weight  of  borax.  (The  filtrate  can  now  be 
tested  for  silver,  adding  a  few  drops  of  hydrochloric  acid, 
and  if  silver  be  present  it  will  be  thrown  down  in  a  white 
flocculent  cloud  as  a  chloride  of  silver.  The  same  should 
be  collected  on  a  filter,  and  can  be  weighed  after  drying  care- 
fully and  then  gently  fusing  in  a  small  porcelain  cup  that 
has  been  previously  weighed,  silver,  75*28;  chlorine,  24'72.) 
Place  in  a  soda-paper  cornet  and  then  fuse  in  the  deep  bore 
on  charcoal  as  in  the  Silver  Assay.  Clean  the  lead  button 
so  obtained,  then  scorify,  and  afterwards  cupel.  Weigh 
the  button  found  after  cupellation  and  fuse  it  on  charcoal 
with  three  times  its  weight  of  silver ;  boil  it  in  a  small 
flask  with  nitric  acid,  and  after  all  action  has  ceased  pour 
off  the  liquor  and  wash  the  fine  dark  powder  with  distilled 


128      ASSAY   OF  SILVEE,   GOLD,   MEECUEY,   ETC.      PART  III. 

water,  add  more  acid,  boil  again,  wash  again,  and  then  re- 
move to  a  small  porcelain  cup  and  allow  it  *to  dry  slowly 
over  the  lamp ;  when  it  is  quite  dry  heat  the  cup  to  a  bright 
red  colour,  and  then  remove  the  gold  (now  pure)  to  the 
balance  and  weigh. 

(6)  Gold  ores  consisting  of  nearly  pure  pyrites,  also 
quartz  mill  concentrations,  cannot  be  washed  with  safety. 

After  the  mineral  has  been  finely  pulverised  take  from 
100  to  1,000  grains,  according  to  the  amount  of  silica 
in  the  ore,  and  roast  it  on  an  ordinary  piece  of 
sheet  iron,  turned  up  at  the  edges  (an  old  worn-out 
miner's  shovel  has  often  been  used  by  the  author),  which 
has  been  previously  coated  with  a  little  moist  fire  clay  ; 
heat  the  sheet  iron  over  a  charcoal  or  coal  fire,  keeping  it 
at  a  dull  red  heat,  and  stir  continually  until  the  smell  of 
sulphurous  acid  is  no  longer  perceptible ;  then  boil  the 
roasted  ore  in  nitric  acid  until  all  soluble  matter  in 
dissolved,  and  proceed  as  in  a. 

Assays  of  the  above  class  are  generally  of  great  com- 
mercial importance,  and  in  such  cases  make  three  assays 
and  take  the  mean  for  the  report. 

(c)  Grold  sands,  such  as  are  found  in  the  rivers  and 
streams  of  California  and  British  Columbia,  and  also  on  the 
sea  beach  in  Oregon,  U.S.A.,  contain  a  large  amount  of 
specular  and  titanic  iron,  and  is  called  '  black  sand  '  by  the 
miners.  The  gold  is  generally  very  fine  and  in  the  form 
of  thin  laminae.  Platinum  and  iridium  are  often  found 
in  the  same  sand. 

The  above  sand  cannot  be  washed  for  assay.  Take  100  to 
1,000  grains,  according  to  the  amount  of  black  sand  in  the 
ore,  and  attack  with  aqua  regia  in  a  flask  ;  boil  for  about  30 
minutes  or  more,  dilute  with  water,  and  filter.  If  gold  is 
present  it  will  now  be  held  in  solution  in  the  filtrate;  remove 
the  filter  and  evaporate  the  filtrate  to  dryness  ;  then  add 
a  little  hydrochloric  acid  and  redissolve  the  dry  salt  in 


PART  III.  GOLD.  129 

warm  water  ;  add  to  the  solution  so  formed  protosulphate  of 
iron,  which  will  throw  down  the  gold  in  the  form  of  a  fine 
dark  precipitate.  The  precipitate  is  seldom  pure,  being 
mixed  with  oxides  of  iron,  and  must  now  be  dried  in  the 
filter  paper  and  both  burned  over  the  lamp  in  a  porcelain 
dish.  Then  mix  the  dried  precipitate  with  three  times  its 
weight  of  lead,  and  its  own  weight  of  borax,  and  one-half 
its  volume  of  soda ;  fuse,  scorify,  and  cupel  as  directed  in 
a.  In  case  platinum,  iridium,  &c.,  are  found  associated 
with  the  gold  an  extra  amount  of  pure  silver  should  be 
added  before  cupellation,  and  the  gold  button  will  be  found 
pure. 

(d)  Grold  from  alluvial  deposits,  ancient  and  modern 
river-beds,  and  placer  washings. 

The  greater  part  of  the  gold  obtained  from  such  sources 
is  usually  found  to  consist  of  coarse  grains,  nuggets,  &c., 
making  it  a  difficult  matter  to  take  a  sample  for  assay. 

A  large  quantity  (20  tons  or  more)  should  be  washed 
through  the  ordinary  gold  sluice-box  (which  has  rifles  or 
stops  charged  with  a  small  quantity  of  mercury)  and  the 
gold  collected ;  then  a  careful  sample  should  be  taken  of 
the  tailings  or  residues  and  three  to  five  different  assays 
made.  Weigh  out  5  Ibs.  (80  oz.)  of  the  tailings  and  wash 
carefully  in  a  batea.  The  concentrated  mineral  must  be 
dried,  and  fused  in  small  portions  (about  2  grains  at 
a  time)  with  twice  its  weight  in  lead,  and  its  own  weight 
in  borax,  and  half  its  volume  of  soda,  and  the  assay  carried 
on  as  in  a. 

The  coarse  gold  first  obtained  should  now  be  weighed 
and  a  sample  taken  for  assay.  The  assay  must  be  conducted 
as  described  on  p.  130  under  the  head  of  <  Gold  Alloys.' 

The  assay  of  the  tailings  or  residues  must  be  added 
to  that  of  the  gold  alloy  first  obtained,  and  the  value  per 
ton  of  the  whole  will  be  ascertained. 


130      ASSAY  OF  SILVER,   GOLD,  MERCURY,  ETC.      PART  III. 

(e)  Furnace  slags  generally  contain  a  very  small  per- 
centage of  gold,  which  at  the  same  time  is  so  minutely 
distributed  through  the  slag  that  a  direct  fusion  is  the 
only  safe  method  to  employ. 

Take  2  grains  slag. 
,,6       „     lead. 
,,     1  grain   borax. 
„    £       „     soda. 


After  a  complete  fusion  in  charcoal  reduce  the  lead  by 
scorification  and  cupel.  The  assay  is  now  finished  as  di- 
rected in  a. 

(/)  Mint  and  jewellers  '  sweeps  '  are  composed  of 
such  various  metals  and  compounds  that  it  is  difficult  to 
select  an  average  sample  for  blowpipe  assay  ;  therefore 

Take  1  00  grains  of  the  sweeps  and  boil  them  in  a  flask 
with  nitric  acid  until  all  the  soluble  matter  is  held  in 
solution.  Dry  the  insoluble  matter  and  the  filter,  and  burn 
the  latter.  After  so  doing  fuse  with  lead  according  to 
directions  in  e,  and  finish  as  directed  in  a. 

\g)  Direct  and  universal  method  for  assaying  gold 
ores  and  minerals,  such  as  telluride  of  gold,  mixed 
sulphides  with  which  gold  is  associated  —  for  instance,  sul- 
phides of  arsenic,  copper,  zinc,  bismuth,  iron,  lead,  &c.&c. 

Take  1*5  grain  of  ore,  mix  with  5  to  10  times  its 
weight  of  pure  litharge,  and  assay  in  precisely  the  same 
way  and  with  the  same  apparatus  as  used  and  described 
in  the  Silver  Assay,  A  (e\  and  purify  the  gold  as  directed 
in  p.  127. 

B  (a).  Fine  gold,  bar  and  ingot  gold,  coins  and  na- 
tive gold,  without  any  adhering  matrix  or  foreign  sub- 
stances. 

All  the  above  are  capable  of  direct  cupellation  after 
an  addition  of  lead.  The  lead  must  be  added  in  the 
following  proportions  :  — 


PART  III. 


GOLD. 


131 


Fineness  of  Gold 
in  Alloy 

Parts  of  Lead  necessary 
to  remove  the  Copper 
by  Cupellation 

Fineness  of  Gold 
in  Alloy 

Parts  of  Lead  necessary 
to  remove  the  Copper 
by  Cupellation 

1000 

5 

700 

27 

975 

7 

650 

30 

950 

9 

.000 

33 

925 

11 

550 

35 

900 

13 

500 

36 

875 

15 

400 

36 

850 

17 

300 

36 

825 

19 

200 

36 

800 

21 

100 

36 

750 

24 

The  gold  coin  of  France  is  900  gold  to  1 00  copper,  and 
that  of  the  U.S.  of  America  the  same.  The  British 
standard  is  gold  916*66  and  the  remainder  copper. 

Weigh  out  1  grain  of  alloy  and  3  grains  of  pure 
silver,  and  wrap  up  in  a  small  piece  of  rolled  assay  lead 
which  has  been  weighed,  and  cupel  on  a  previously  pre- 
pared cupel  (see  fig.  54,  Silver  Assay).  The  heat  required 
is  greater  than  that  which  is  employed  in  the  Silver  Assay, 
as  the  alloys  of  gold,  copper,  and  silver  require  a  high 
temperature  for  cupellation.  Grold  suffers  but  a  slight 
loss  by  volatilisation.  When  the  cupellation  is  complete 
remove  the  button  with  the  pliers  and  clean  the  lower 
surface  with  a  small  brush ;  then  beat  the  button  on  the 
steel  anvil  until  a  thin  sheet  has  been  obtained. 

The  last  operation  can  be  facilitated  by  placing  the 
assay  on  a  piece  of  charcoal  and  heating  it  to  redness  and 
then  beating  it  out.  When  thin  enough  anneal  again  and 
twist  the  small  sheet  of  alloy  into  the  form  of  a  coil,  and  boil 
in  a  small  flask  or  test  tube  with  about  -J  oz.  of  nitric  acid 
(of  1'3  specific  gravity)  for  5  to  10  minutes;  then  add  a  little 
pure  water  and  pour  off  the  nitrate  of  silver ;  again  add  J  oz. 
of  nitric  acid  (of  1'3  specific  gravity)  and  boil  until  all 
action  has  ceased.  Then  pour  off  the  acid,  add  an  ounce 

K   2 


132      ASSAY   OF  SILVER,  GOLD,   MERCURY,   ETC.      PART  III. 


of  pure  water,  and  boil  for  a  minute.  Pour  off  the  hot 
water  and  fill  the  tube  with  cold  water,  and  remove  the 
gold  into  a  small  pipe-clay  crucible  by  first  placing 
the  crucible  on  the  mouth  of  the  flask  or  test  tube  (see 

FIG.  61.          FIG.  62.      fig.  61),  then  inverting-  them  both 
(Half size.)        (Halfsize.)  ^  fig'_  ^      The  ~«    ^  (eyen 

if  in  a  fine  powder)  soon  settle  to 
the  bottom  of  the  cup,  and  it  can  be 
quickly  done  if  the  operator  will 
slightly  tap  the  sides  of  the  tube 
with  his  finger  nail,  remove  the  tube 
from  the  crucible,  and  carefully  pour 
off  the  water,  and  then  allow  to  dry 
slowly,  and  when  dry  heat  the  cruci- 
ble to  a  bright  redness  over  the  spirit 
lamp,  and  then  remove  the  gold  to 
the  balance  and  weigh  as  pure. 

If  the  alloy  is  only  about  800 
(or  under)  fine  take  0*7  gr.  for  as- 
say, and  cupel  first  with  the  neces- 
sary quantity  of  lead,  and  add  the 
charge  of  silver  with  2  grains  of  lead  when  the  cupel- 
lation  is  nearly  complete. 

Chemically  pure  gold,  even  when  boiled  3  times  in 
nitric  acid,  still  retains  a  trace  of  silver,  and  1,000  parts 
of  pure  gold,  after  being  carefully  cupelled  and  parted, 
will  weigh  1000*2.  The  amount  is,  however,  so  small 
that  it  is  only  deducted  in  the  Mint  and  Gold  Assay 
Office  reports. 

(6)  Gold  nuggets  and  fine  gold  dust. 

Take  1  grain,  and  fuse  on  charcoal  with  1  grain  borax 

and  ^  grain  nitre,  and  after  the  bead  is  thoroughly  cleaned 

by  the  fusion  proceed  as  in  B  (a).     In  assaying  nuggets 

cut  them  in  two,  and  get  an   average  sample  if  possible. 


PART  III.     ,  GOLD.  133 

The  outside  is  generally  deceptive,  and  frequently  coated 
with  foreign  substances,  such  as  silicates,  iron  oxides,  &c. 

(c)  Worn-out    copper    plates  that  have  been  used  in 
gold  amalgamation  works,  copper  coins,  wire,  and  cement. 

Weigh  out  10  grains,  and  attack  with  dilute  nitric 
acid  ;  after  a  thorough  boiling  and  decantation,  dry  the 
fine  dark  residue,  add  to  it  pure  silver  and  lead,  cupel,  and 
then  finish  the  assay  as  in  B  (a). 

(d)  Gold  containing  palladium  and  not  more  than  10 
per  cent,  of  platinum. 

Cupel  1  grain  of  alloy  with  4  grains  of  silver  and  the 
proper  quantity  of  lead  (see  table,  p.  131).  Attack  with 
nitric  acid  three  times,  and  the  gold  residue  will  be  found 
pure. 

(e)  Gold  containing  more  than  10  per  cent,  of  platinum. 
Dissolve  1  grain  of  the  alloy  in  nitro-hydrochloric  acid 

(3  parts  hydrochloric  and  1  part  nitric  acid).  Whilst  the 
solution  is  still  warm  add  chloride  of  ammonium  to 
it,  and  evaporate  the  whole  to  dryness  at  a  moderate 
temperature.  The  dried  salt  is  then  washed  on  a  filter  with 
alcohol  of  70°  to  80°  until  a  fresh  addition  of  it  is  no  longer 
coloured  yellow.  The  gold  is  by  this  means  dissolved  out. 
Add  water  to  the  alcoholic  solution,  remove  the  alcohol  by 
evaporation,  and  then  precipitate  the  gold  with  protosul- 
phate  of  iron  according  to  the  methods  described  in  A  (c). 

(/)  Gold  containing  iridium.  Dissolve  1  grain  in 
aqua  regia.  The  iridium  remains  behind  in  the  form  of  a 
black  powder,  which  can  be  washed  and  dried  and  the 
percentage  of  iridium  estimated.  The  gold  can  be  esti- 
mated as  in  A  (c). 

If  the  alloy  contains  copper  it  must  be  first  cupelled 
with  about  5  parts  of  lead,  and  the  last  trace  of  lead 
removed  by  fusing  it  on  charcoal  with  boracic  acid. 

(#)  Gold  with  platinum  and  silver. 


134      ASSAY  OF  SILVER,   GOLD,   MERCURY,   ETC.     PART  III. 

Plattner  recommends  the  following  plan  : — When  the 
silver  has  to  be  determined,  it  must  be  extracted  by  sul- 
phuric acid.  To  do  this  with  proper  accuracy  the  alloy 
should  contain  for  1  part  of  gold  and  platinum  not  less 
than  1£  nor  more  than  2  parts  of  silver,  because  some 
platinum  seems  to  dissolve  with  more  silver.  When  silver 
is  lacking,  an  accurate  quantity  of  pure  silver  must  be 
added,  and  if  gold  is  lacking  the  alloy  must  be  molted 
with  pure  gold,  to  secure  the  necessary  proportions  of  the 
metals. 

One  grain  of  the  alloy  being  weighed  out  and  brought  to 
the  proper  proportions  by  fusing  it  with  gold  or  silver  and 
borax  glass  on  coal,  the  button  is  beaten  as  thin  as  pos- 
sible, heated  to  redness,  and  rolled  up. 

After  being  weighed,  to  see  that  no  mechanical  loss 
has  occurred,  it  is  covered  with  concentrated  sulphuric 
acid  in  a  porcelain  vessel  and  boiled  for  10  minutes.  After 
cooling,  the  acid  solution  containing  sulphate  of  silver 
is  decanted,  and  the  porous  metallic  residue  boiled  five 
minutes  longer  with  fresh  acid  to  complete  the  separa- 
tion of  the  silver.  The  remaining  roll  is  boiled  with 
distilled  water,  dried,  ignited,  and  weighed  ;  the  difference 
gives  the  weight  of  silver.  The  gold  and  platinum  are 
then  separated  according  to  B  (d). 

(h)  Grold  containing  rhodium. 

Weigh  1  grain  of  alloy,  dissolve  in  aqua  regia,  and 
precipitate  the  gold  with  protosulphate  of  iron,  as  in  A  (c). 

The  rhodium  remains  in  solution. 

(i)  Gold  with  lead,  bismuth,  gun  metal,  antimony, 
zinc,  brass,  &c.,  is  assayed  according  to  Class  B  in  Silver 
Assay.  If  much  antimony  or  zinc  is  present  the  alloy 
should  be  fused  on  charcoal  with  borax  before  cupellation. 

(j)  A  rapid  method  of  making  an  approximate  assay 
of  gold  coins,  nuggets,  gold  dust,  or  bullion. 


PART  III.  GOLD  AND  MERCURY.  135 

Take  1  grain  of  the  alloy,  melt  it  with  4  grains  of 
silver,  1  grain  borax,  0*5  grain  nitre,  on  charcoal. 

After  a  thorough  fusion  beat  it  out  and  dissolve  as 
usual  in  nitric  acid.  The  assay  can  be  made  in  a  few 
minutes,  and  will  be  within  5  to  10  thousandth  of  the  true 
standard. 

C  (a).  Gold  amalgams  are  first  retorted  according  to 
Class  C  in  assay  of  mercury.  Then  the  alloy  is  fused 
with  a  small  quantity  of  borax  and  nitre  on  charcoal. 
One  grain  of  the  fused  metal  is  weighed  out  and  treated 
as  in  B  (a). 

MERCURY. 

Mercury  occurs  in  small  fluid  globules  scattered 
through  its  gangue. 

Specific  gravity  =13*5 6.  Lustre  metallic.  Colour 
tin  white.  Becomes  solid  at  39°  Fahr.  below  zero,  and 
crystallises  in  octahedrons.  Volatilises  at  64°  Fahr.  and 
entirely  so  at  662°  Fahr. 

The  rocks  affording  the  metal  and  its  ores  are  mostly 
clay  shales  or  schists  of  different  geological  ages. 

Cinnabar,  or  sulphide  of  mercury. 

Contains  sulphur  13*8  per  cent.,  mercury  86*2  per 
cent. 

Cinnabar  is  of  a  bright  red  or  reddish  brown  colour, 
and  is  sometimes  impure  from  clay,  oxide  of  iron,  and 
bitumen. 

Tiemannite,  or  selenide  of  mercury. 

Contains  selenium  28*4  per  cent.,  mercury  71*6  per 
cent. 

Calomel,  or  flour  mercury. 

Contains  chlorine  15-1  percent.,  mercury  84*9  per  cent. 

Mercury  is  also  found  combined  in  various  proportions 
with  sulphides  of  zinc,  and  also  with  iodine. 


136      ASSAY  OF  SILVEE,   GOLD,  MERCURY,   ETC.      PART  III. 


Amalgams. 

Mercury  with  gold,  silver,  and  copper  in  the  form  of 
amalgam  has  been  frequently  found  in  nature,  but  the 
proportions  vary  greatly  in  different  localities,  and  no 
correct  formula  has  yet  been  arrived  at. 

In  metallurgical  products  mercury  is  obtained  in 
combination  with  many  metals,  the  principal  of  which  are 
gold,  silver,  copper,  lead,  bismuth,  zinc,  iron,  tin,  &c.,  and 
under  certain  conditions  it  combines  with  sodium  and 
potassium. 

Amalgams  of  silver,  bismuth,  &c.,  are  extensively  used 
by  dentists. 

In  the  practice  of  medicine  mercury  is  largely  used, 
the  general  forms  being  metallic,  subchloride,  chloride,  and 
oxide.  Mercury  is  nearly  always  determined  by  distillation, 
but  before  making  an  assay  of  its  ores  the  operator  should 
examine  with  great  care  the  ore  in  question  with  regard 
to  metallic  globules  of  mercury,  and  if  such  are  found  to 
exist  (which  is  frequently  the  case,  especially  in  the  ores 
from  Californian  mines)  several  ounces  of  the  ore  should 
be  weighed,  and  then  crushed  up  and  vanned  carefully  in 
a  horn  spoon,  or  porcelain  bowl,  and  the  metallic  mercury 
collected  on  blotting  or  filter  paper,  which,  when  dry,  weigh, 
and  add  the  percentage  so  found  to  what  is  afterwards 
obtained  by  assay  from  the  remainder. 

The  residue  both  of  water  and  crushed  ore  must  be  all 
carefully  saved,  the  water  evaporated,  and  when  dry  mix 
and  take  a  sample  for  assay. 

Assay  for  Mercury. 

The  compounds  to  be  examined  are  divided  into  three 
classes,  and  will  be  called  A,  B,  C. 


PART  III.  MERCUKY.  137 

Class  A, 

Consisting  of  metallic  mercury. 

,,  cinnabar   (artificial  slate  forms  what  is  called 

vermillion). 
, ,  tiemaimite. 

,,  sub-oxide. 

,,  protoxide. 

,,  mixed  sulphides,  &c. 

Class  B. 

Consisting  of  calomel  (sub-chloride). 

„  chloride  of  mercury  (corrosive  sublimate). 

,,  iodide  of  mercury. 

Class  C. 

Consisting  of  amalgams  of  gold,  silver,  copper,  lead,   zinc, 
tin,  &c.  &c. 

Class  A. — The  assay  is  conducted  as  follows  : — 
Keduce  the  ore  to  a  fine  powder,  so  that  the  sample  to 
be  assayed  will  all  pass  through  a  sieve  of  2,000  holes  to 
the  linear  inch.  Weigh  out  from  10  to  20  grains  of  ore, 
according  to  its  richness;  intimately  mix  with  5  to  10 
times  its  weight  of  finely  powdered  litharge,  and  distil  in 
a  small  glass  retort  over  the  spirit  lamp. 

Eetorts  of  the  following  size  and  shape  (see  fig.  63) 
have  been  found  to  give  very  accurate  results,  and  can  be 
made  by  the  operator  from  hard  flint  glass  tubing  by 
closing  one  end  over  the  lamp  and  then  bending  it,  when 
heated,  to  the  required  angle.  The  retort  a,  or  cup,  is 
made  f  inch  in  length,  and  neck  b  of  same  f  inch,  and  J 
inch  in  diameter.  The  neck  is  fitted  into  a  good  tight 
cork,  and  placed  firmly  in  the  top  of  a  glass  tube  c  of 
about  2  J  inches  in  length  and  T%-  of  an  inch  in  diameter, 
tapering  at  the  bottom  to  J  of  an  inch.  The  tube  is  also 
bent  slightly,  to  facilitate  the  collection  of  mercurial 
vapour  in  the  receiver  d.  The  end  of  the  tube  is  kept 
immersed  during  the  heating  of  the  assay  in  a  small  cup 
or  capsule  containing  water,  and,  as  the  operation  occupies 


138      ASSAY   OF  SILVER,   GOLD,   MERCURY,   ETC.      PART  III. 

only  a  few  minutes,  the  retort  and  condensing  tube  can 
be  held  with  a  small  pair  of  wooden  tongs  without  any 
inconvenience. 

FIG.  63.     (Full  size.) 


Before  the  retort  is  used  expel  all  the  moisture  by  a 
thorough  drying.  The  above-shaped  retorts  are  easily 
charged  by  pouring  in  the  ore  and  litharge  from  a  small 
mixing  spoon,  and  then  connecting  it  by  means  of  the  cork 
'with  the  condensing  tube. 

The  retort  is  heated  very  gradually  at  first  over  the 
spirit  lamp,  and  finally  the  heat  is  raised  until  the  assay  is 
fused,  and  the  glass  softens  and  nearly  melts.  The  greater 
portion  of  the  mercury  will  be  found  in  the  receiving  cup, 
but  small  particles  will  generally  be  found  in  the  condens- 
ing tube.  Heat  the  tube  slightly,  which  has  the  effect  of 
bringing  the  minute  globules  of  mercury  together  ;  then 
remove  them  carefully  with  a  feather  and  add  them  to  the 
globules  in  the  cup.  The  retort  and  its  fused  contents 
should  now  be  broken  up  in  a  horn  spoon  or  porcelain  dish, 
in  which  a  small  quantity  of  water  has  been  previously 
added,  and  after  vanning  examine  carefully  with  a  magnify- 


PART  III. 


MERCURY. 


139 


ing  glass,  to  see  if  any  globules  can  be  found.     If  they  are 
the  assay  should  be  repeated. 

Slightly  heat  the  receiving  cup  over  the  lamp,  taking 
care  to  have  it  half  full  of  a  FIG.  64.  (§  size.) 
water.  The  fine  globules  of 
mercury  will  then  unite  into 
one  globule.  Pour  off  the 
water  and  dry  the  mercury 
with  blotting  paper,  and  re- 
move to  a  small  weighing 
cup  and  ascertain  its  weight 
on  the  balance.  The  mer- 
cury so  obtained  can  be  con- 
sidered pure. 

Class  B. — Cannot  be  re- 
duced by  litharge  alone,  and 
a  different  reducing  agent  as  well  as  shaped  retort  must  be 
employed.  Take  of  the  finely  powdered  ore  or  product  10 
grains,  and  mix  it  with  about  3  times  its  volume  of  neutral 
potassium  oxalate  and  1  volume  of  potassium  cyanide, 
and  distil  in  a  retort  of  the  following  description  (see  fig. 
64) : — A  small  bulb-shaped  retort  a,  constructed  of  thick, 
hard  flint  glass,  about  ^  inch  in  diameter  at  its  widest 
part  and  j  inch  in  depth  ;  length  of  neck  b  about  J  inch  ; 
diameter  of  the  latter  about }  inch.  The  neck  is  fitted  with 
a  good  cork  and  placed  firmly  on  the  top  of  a  glass  tube 
about  2  J  inches  in  length,  and  -fa  of  an  inch  in  diameter 
at  the  top,  tapering  at  the  bottom  to  J  of  an  inch.  The 
mixture  having  been  placed  on  the  retort,  the  heat  is 
applied  very  slowly  and  with  great  care  at  first,  to  avoid 
the  rapid  reaction  which  would  otherwise  take  place.  The 
distillation  only  occupies  a  few  minutes,  and  the  assay 
should  be  completed  and  the  mercury  collected  and 
weighed  with  all  the  precautions  mentioned  in  Class  A. 


140      ASSAY  OF  SILVER,   GOLD,  MERCURY,   ETC.      PART  III. 

Class  G. — Native  and  artificial  amalgams,  as  well  as 
dentists'  products,  are  often  so  hard  and  compact,  as  well 
as  mixed  with  lead,  bismuth,  zinc,  copper,  &c.,  that  a 
correct  determination  cannot  be  arrived  at  by  direct 
distillation,  owing  to  the  swelling,  spitting,  and  spurting 
that  take  place  soon  after  the  application  of  heat.  An 
approximative  test  should  be  made  on  charcoal  or  in  a 
small  crucible  or  glass  tube,  and  if  the  spurting  is  found 
to  be  so  violent  that  the  amalgam  cannot  be  distilled 
without  loss,  it  should  be  crushed  up  in  the  agate  mortar 
and  then  placed  in  the  retort  for  distillation.  In  many 
cases  the  latter  plan  is  most  difficult,  and  in  some  im- 
possible without  losing  a  large,  portion  of  the  sample.  In 
such  a  case  weigh  out  one  equal  part  of  pure  mercury, 
mix  it  with  the  assay  sample,  and  then  crush  it  in  the 
agate  mortar.  The  amalgam  will  then  be  found  to  be  in 
a  semi-fluid  condition,  in  which  state  remove  it  to  the 
iron  retort,  and  the  mercury  can  be  evaporated  and 
collected  without  danger  of  loss  in  spitting,  and  the 
weight  of  the  mercury  added  deducted  from  the  total  found. 

In  assaying  amalgams  make  two  assays. 

1st.  Distil  the  amalgam,  then  condense  and  collect 
the  mercury,  and  weigh. 

2nd.  Subject  the  amalgam  to  the  blowpipe  flame  either 
in  an  open  cup  or  dish,  and  take  the  loss  of  weight  to  be 
mercury.  The  heat  never  to  be  sufficient  to  fuse  the 
retorted  metal,  else  a  loss  will  arise  from  the  volatilisation 
of  lead,  zinc,  silver,  &c.,  all  of  which  are  frequently  found 
combined  with  mercury. 

The  last  method  will  be  found  to  be  very  accurate 
when  the  amalgams  consist  of  nearly  pure  silver  or  gold 
combined  with  the  mercury,  but  if  other  metals  exist  with 
them  the  results  are  very  uncertain. 

It  serves,  however,  not  only  as  an  approximate  assay, 
but  as  a  check  on  the  distillation  assay. 


PART  III.  MERCUEY.  141 

The  retorts  used  for  the  determination  of  the  amount 
of  mercury  contained  in  amalgams  must  be  differently 
constructed  to  those  which  are  used  for  Classes  A  and  5,  and 
are  best  made  of  cast  steel,  which  is  afterwards  turned 
in  the  lathe  to  the  required  form. 

FIG.  65.     (f  size.) 


The  retort  is  made  1  inch  in  height,  which  includes 
the  cup  and  cap ;  the  neck  about  2  inches  in  length,  having 
a  gentle  taper  towards  the  end,  w^hich  is  made  to  fit  into 
a  good  cork  which  has  been  previously  placed  in  the  glass 
condenser.  (See  fig.  65,  cross  section  of  the  steel  re- 
tort with  glass  condenser.) 

Fig.  66,  view  of  the  cup  and  distillation  pipe  of  the 
amalgam  retort. 

Fig.  67,  view  of  the  FlG-  66-    (Ful1  size-) 

receiving  cup    of    the 
amalgam  retort. 

Fig.  6 8,  view  of  the 
glass  condenser. 

Ten  to  30  grains  of 
the  amalgam  to  be 
examined  is  weighed, 
wrapped  up  in  a  small 
piece  of  tissue  paper, 
and  (the  weight  of  ash, 

contained  in    a    similar    piece  of  the  same  paper,  must 
always    be    determined   in   a   quantitative   assay)   placed 


142      ASSAY  OF  SILVER,   GOLD,   MERCURY,   ETC.      PART  III. 


in  the  receiving  cup  (fig.   67).     The  cap  is  now   placed 

,^•^7-     firmly  on.     The  joint  being  perfectly  air-tight, 
no  luting  is  necessary. 

The  condenser  (fig.  68)  is  attached,  and 
the  retort  placed  in  the  charcoal  furnace,  which 
has  now  to  be  held  firmly  by  the  holder.  See 

fig.  69,   a   side  view    of  the  holder  and  charcoal  furnace, 

showing  end  of  retort. 

FIG.  68.    (Full  size.) 


Fig.    70,   a   top   view    of  the    charcoal   furnace    and 
holder. 

The  furnace  is  now  brought  near  the  blowpipe  lamp 

FIG.  G9.    (Half  size.) 


and  the  end  of  the  condenser  kept  immersed  in  water  con- 
tained in  a  small  porcelain  crucible. 

The  heat  is  applied  very  quietly  at  first,  but  in  a  few 
minutes  a  strong  R.F.  may  be  applied  through  the  hole 


PART  III. 


MERCURY. 


143 


in  the  lower  part  of  the  furnace.  Flames  will  soon 
be  seen  coming  out  of  the  top  hole  of  the  furnace,  and 
the  retort  will  be  found  to  be  red  hot.  Keep  it  so  for 
about  two  minutes,  then  cease  blowing  and  allow  the  retort 
to  cool. 

See  fig.  71,  sectional  view  of  blowpipe  stand  and 
lamp,  with  flame  playing  on  the  amalgam  retort,  which 
has  been  placed  in  the  charcoal  furnace  ;  also  a  view 
showing  the  position  of  the  condenser  and  receiver  of  the 
mercurial  vapour. 

FIG.  70.     (Half  size.) 


The  whole  operation  does  not  take  ten  minutes,  and 
although  the  retort  may  appear  large,  the  operator  will 
find  no  difficulty  even  in  obtaining  a  white  heat  if 
necessary ;  and  in  a  few  minutes  the  assay  is  completed. 

The  mercury  is  collected  and  weighed  according  to  the 
methods  laid  down  in  Class  A* 

Most  accurate  results  will  be  obtained  by  following  the 
above  instructions. 

In  Plattner's  *  Manual  of  Qualitative  and  Quantitative 
Analysis  with  the  Blowpipe,'  by  Prof.  T.  Kichter,  and 
translated  by  Henry  B.  Cornwall,  and  published  1873, 


144      ASSAY   OF  SILVER,    GOLD,   MERCURY,   ETC.      PABT  III. 

on  p.  509  will  be  found  the  following  under  the  head 
of  '  Assay  for  Mercury : ' — 

'  This  assay,  essentially  the  same  as  that  proposed 
by  Domeyko  and  described  in  the  "  Berg-  und  Hiittenm.- 
Zeitung,"  1845,  No.  20,  is  very  simple  and  exact/ 

A  glass  tube,  about  3  lines  in  diameter  and  7  to 
8  inches  long,  of  not  too  thin  glass,  is  bent  as  shown 

FIG.  71.1     (I  size.) 


in  fig.  72,  and   closed  at  one  end,    leaving  the    shorter 
arm  a  1J  to  2  inches  long. 

The  tube  is  thoroughly  dried,  and  then  from  500  to 
3,000  milligrammes  of  finely  powdered  ore,  according  to  its 
richness,  intimately  mixed  with  5  to  10  grammes  litharge, 
1  The  three  different  retorts,  also  charcoal  holder,  all  originally  de- 
signed by  the  author,  were  made  by  L.  Cassella,  147  Holborn  Bars,  E.G., 
where  similar  ones  can  now  be  procured. 


PART  III.  MERCURY.  145 

being  introduced  into  it,  the  lower  end  is  gradually  heated 
over  the  spirit  lamp  until  the  whole  mass  is  fused  and 
the  glass  begins  to  soften.  The  moisture  that  may  be 
present  condenses  in  the  middle  of  the  tube,  while  the 
mercury  will  settle  as  a  thin  film,  sometimes1  scarcely 
perceptible,  on  the  sides  of  the  glass  (see  fig.  72). 
When  all  of  the  mercury  has  been  sublimed  the  tube  is 
carefully  heated,  so  as  to  concentrate  the  mercury  as  much 
as  possible  to  a  ring  at  6 ;  the  tube  is  allowed  to  cool,  cut 
off  with  a  file  close  to  the  ring,  and  the  mercury  then 
brushed  together  to  one  drop  and  transferred  to  a  weighed 
capsule. 

FIG.  72.    (Half  size.) 


In  this  way  0*05  per  cent,  of  mercury  can  be  very 
readily  determined,  and  the  nature  of  the  gangue  has  no 
influence  upon  the  result.  The  excess  of  litharge  serves 
not  only  to  oxidise  the  sulphur  and  selenium,  but  also  to 
remove  the  arsenic,  antimony,  and  bitumen  so  frequently 
found  in  ores  of  mercury,  and  the  resulting  metal  is  so 
pure  that  it  can  be  very  easily  and  perfectly  united  in  one 
drop. 

COPPER. 

Copper  is  a  metal  having  a  metallic  lustre  and  of  a 
copper-red  colour.  It  has  a  streak,  metallic  shining,  and 
is  ductile  and  malleable  with  a  hackly  fracture. 

Hardness,  2*5  to  3.  Specific  gravity,  8*838  when  native. 


146      ASSAY   OF   SILVER,   GOLD,   MERCURY,   ETC.      PART  III. 

The  principal  ores  of  copper  are — 

'Copper  glance  .     containing     797    per  cent,  copper. 

Chalcopyrite      .  ,,  34 '4                ,, 

Bornite      .     ,<  .  .                   „  557 

Bournonite        .  .             ,,  13 '0                 ,, 

iFahlerz     .         .  .             ,,  30  to  48 

Covelline  .     .    .  -  .             „  667 

I  Wolfsbergite     ,  ,,  24 '9                 ,, 

IDomeykite  (copper  arsenide),,  71 '6                ,, 


-  Copper  regulus,  copper  speiss,  &c. 


^  f  Red  copper      ..         .     containing  887                „ 

||  I  Malachite        ',.  !      .,            „  57  '3 

§i1  Azurite     .         .                       „  55'1                 „ 

•^  ^  Cyanosite.         .        ,^             ,,  25  '3                 „ 

.|  g  |  Phosphate  of  copper              ,,  30  to  56             ,, 

•"I  |  JArseniate.         .         ,     .         ,,  25  ,,  50             „ 

^  ^  Chromate,  vanadate,  and  silicate 
^       of  copper,  slags,  &c. 

Assay. 

The   assay  for  copper  is   divided  into  three  classes, 
called  A,  B,  and  C. 
Class  A  . 

Consists  of  ores  and  products  in  which  the  copper  is  com- 
bined with  volatile  substances,  such  as  sulphur,  arsenic, 
and  selenium. 

Clans  B. 

Consists  of  ores  and  products  in  which  the  copper  exists  as 
an  oxide  or  is  combined  with  chlorine. 

Class  C. 
Consists  of  alloys  containing  copper. 

Copper  is  separated  by  the  blowpipe  from  its  matrix  or 
compounds  by  first  freeing  it  from  its  combinations  with 


PART  III.  COPPEK.  147 

sulphur,  &c.,  by  roasting  the  finely  crushed  substance  with 
powdered  charcoal  or  graphite.  The  oxidised  mineral  is 
then  fused  with  soda,  borax  glass,  and  a  small  quantity  of 
test  lead.  The  soda  reduces  the  copper  oxides  to  metal, 
and  the  lead  assists  in  the  collection  of  the  copper  in  the 
shape  of  a  globule.  The  alloy  of  lead  and  copper  is  then 
fused  on  charcoal  with  boracic  acid,  which  dissolves  the  lead 
and  leaves  a  copper  button. 

The  fire  assay  of  copper  is  of  great  use  to  the  smelter 
and  miner.  By  observing  the  behaviour  of  the  small 
assay  sample  under  treatment,  and  by  examining  the  copper 
prill  or  button  obtained  by  the  assay,  a  conclusion  can  be 
arrived  at  in  regard  to  the  quantity  as  well  as  the  quality 
of  the  copper  which  will  be  produced  from  similar  ores 
or  products  treated  on  a  large  scale  in  smelting  works. 

The  fire  assay  always  yields  a  smaller  percentage  of 
copper  than  that  which  is  found  by  analysis  or  by  assays 
made  by  the  volumetric  methods.  With  a  little  practice 
and  care  the  following  methods  of  assaying  have  been 
found  to  give  equally  as  good  results  as  the  German  fire 
assay.  The  latter  is  considered  more  accurate  than  the 

English  fire  assay  :  — 

Class  A. —  Take  1J  grain  of  the  finely  powdered  ore 

and  mix  in  the  agate  mortar  with  3  to  4          FIG.  73. 

times  its  volume  of  dry  charcoal  powder, 

or  with   |    grain  graphite  powder    (N.B. 

the   graphite   used  in    an  ordinary    lead 

pencil  answers  very  well) ;  place  the  assay  in  a  small  clay 

capsule. 

The  clay  capsule  should  be  painted  with  reddle  before 

using  (see  fig.  73). 

The  assay  is  now  ready  for  roasting. 

Place  the  roasting  cup  on  the   holder  above  the  lamp 

flame  (see  fig.  74). 

L   2 


148      ASSAY  OF  SILVER,   GOLD,   MERCURY,  ETC.      PART  III 

(The  best  fuel  to  use  is  common  methylated  spirit,  as 
oil  is  apt  to  cover  the  cup  with  lampblack.) 

Place  over  the  roasting  cup  a  small  hollow  cone  made 
of  thin  sheet  iron,  which  confines  the  heat  and  makes  a 
mild  form  of  a  furnace. 

The  roasting  is  nearly  complete  in  10  minutes.  Kemove 
the  assay  again  to  the  agate  mortar,  and  mix  it  with  3  times 
FIG.  74.  (Half  nat.  size),  its  volume  of  dry  powdered  charcoal,  or 
J  a  grain  of  graphite  powder,  and  place 
it  over  the  lamp  as  before,  and  conti- 
nue the  heat  until  no  fumes  of  sulphur 
or  arsenic  are  observed  after  stirring 
with  a  small  piece  of  iron  wire.      For 
the  success  of  the  assay  it  is  neces- 
sary that  all  the  sulphur  should  be  eli- 
minated ;   therefore,  to  be  certain  of 
the  assay,  remove  the  cone,  turn  the 
support  partly  to  one  side  and  a  little 
below  or  on  a  level  with  the  lamp  wick,  and  apply  to  the 
bottom  of  the  cup  a  strong  O.F.  for  a  few  moments. 

The  copper  is  now  in  the  state  of  oxide  mixed  with 
various  other  metallic  oxides  and  earthy  matters,  and  the 
assay  will  be  finished  according  to  the  plan  adopted  in 
Class  B. 

Class  B. —  The  roasted  ore,  product,  or  mineral,  having 
been  reduced  to  the  state  of  a  fine  powder,  is  mixed  in 
the  following  proportions  with  a  reducing  flux : — 

Ore1    ....  1 '5  grain. 

Soda    .         .         .  3'0  grains. 

Borax  glass          .         .  0'5  grain. 

Test  lead     .         .         .  0'5      „ 

1  Ore  belonging  to  Class  A  that  has  been  weighed  once  need 
not  be  so  again. 


PART  III.  COPPER.  149 

The  assay  is  then  removed  to  a  small  soda-paper 
cornet,  previously  placed  in  a  deep  bore  on  a  piece  of  char- 
coal. A  mild  R.F.  is  first  applied,  and  then  finally  a 
strong  flame  to  unite  all  the  metallic  globules.  This 
having  been  accomplished,  the  assay  is  allowed  to  cool, 
and  the  button  is  separated  from  the  slag  by  enclosing  it, 
in  a  piece  of  thick  paper  and  gently  hitting  it  on  the  steel 
anvil  with  the  hammer,  after  which  it  is  treated  as  Class  C. 

Class  C. — (a)  Alloy  of  copper  and  lead. 

The  button  obtained  from  Class  B  is  now  ready  for 
refining,  and  will  be  assayed  in  a  similar  manner  to  a 
copper  and  lead  alloy,  viz.  a  small  hole  is  made  in  a 
piece  of  sound  charcoal,  and  boracic  acid,  equal  in  weight 
to  the  crude  button  containing  copper,  is  melted  on  the 
charcoal.  When  the  boracic  acid  is  in  a  state  of  fusion 
the  copper  button  is  added.  The  E.F.  is  applied  until 
the  button  and  flux  are  dissolved  ;  then  an  O.F.  is  applied, 
and  continued  until  the  lead  has  absorbed  oxygen  and 
has  been  taken  into  combination  with  the  borax,  and  the 
remaining  copper  assumes  a  greenish  colour. 

The  copper  button  is  allowed  to  cool,  and  is  separated 
from  its  surrounding  impurities  by  folding  it  in  a  thick 
piece  of  paper  and  striking  it  gently  on  the  steel  anvil 
with  a  hammer. 

The  slag  should  be  examined,  to  see  if  it  has  a  reddish 
colour  ;  if  it  has,  it  must  be  remelted  with  a  strong  R.F. 
on  charcoal,  and  any  globule  of  copper  so  obtained  added 
to  the  larger  button.  A  pure  button  of  copper  should  be 
malleable. 

If  the  copper  ore  or  compound  contains  either  gold 
or  silver,  they  will  be  found  alloyed  with  the  button  so 
obtained.  To  test  for  the  above  the  button  is  cupelled 
and  treated  according  to  directions  given  in  the  Silver 
Assay. 


150      ASSAY   OF  SILVER,   GOLD,   MKRCURY,  ETC.      PART  III. 

(6)  Alloy  of  copper  and  antimony. 

Weigh  out  1J  grain  of  the  alloy  and  fuse  in  a  small 
bore  on  charcoal.  The  O.F.  alone  is  used  after  the  assay 
melts,  and  it  is  continued  until  the  antimony  is  burnt 
away. 

The  button  obtained  is  then  beaten  on  the  anvil,  and 
it  should  be  malleable  and  not  fracture  if  hammered  out 
from  two  to  three  times  its  diameter.  The  button  should 
also  be  tested  for  gold  and  silver. 

N.B.  Alloys  of  copper  and  tin,  consisting  of  bronze, 
bell  and  gun  metal,  &c.,  also  alloys  consisting  of  copper 
with  iron,  nickel,  cobalt,  zinc,  and  bismuth,  and  sometimes 
containing  lead,  antimony,  and  arsenic,  have  afforded  Platt- 
ner  results  not  sufficiently  satisfactory  for  a  quantitative 
assay.  The  author  has  also  experienced  similar  trouble 
in  the  quantitative  separation  of  copper  from  the  above 
alloys,  and  at  present  he  cannot  recommend  any  method 
to  be  used  by  the  blowpipe  beyond  a  qualitative  determi- 
nation. 

LEAD. 

Lead  has  occasionally  been  found  native,  but  only  in 
small  quantities  in  the  form  of  thin  plates  and  small 
globules.  It  has  a  hardness  of  1*5  and  a  specific  gravity 
of  11*44  when  pure,  with  a  metallic  lustre  and  a  lead- 
grey  colour,  and  is  both  malleable  and  ductile. 

The  ores  of  lead  are  numerous ;  the  principal  one,  called 
galena,  contains,  when  pure,  lead  86'55  per  cent,  and  sul- 
phur 13-45  per  cent. 

For  the  purposes  of  assaying  the  ores  of  lead  by  the 
blowpipe  the  method  adopted  has  been  divided  into  two 
classes,  according  to  the  composition  of  the  ore  to  he  ex- 
amined, and  will  be  called  A  and  B. 


PART  III.  LEAD.  1,51 

Class  A. — Comprises  galena  and  all  leader es  contain- 
ing either  arsenic,  phosphorus,  or  sulphur. 

Class  B. — Comprises  all  ores  of  lead  and  plumbi- 
ferous  substances  which  are  free  from  sulphur  and 
arsenic,  or  contain  only  traces  of  the  latter.  Litharge, 
carbonate  of  lead  and  minium,  are  the  chief  substances 
which  come  under  this  class. 

Assay. 

Lead  is  extracted  from  its  matrix  by  fusing  the  finely 
powdered  mineral  with  metallic  iron  and  a  fluxing  and 
reducing  agent  in  a  small  crucible  placed  in  the  charcoal 
melting  furnace.  The  earthy  matters  and  non-reducible 
oxides  and  sulphides  are  slagged  off,  and  a  button  of 
metallic  lead  will  be  found  on  the  bottom  of  the  crucible. 

The  assay  of  lead  by  fire  is  always  attended  with  a 
heavy  loss,  as  lead  volatilises  readily  when  strongly  heated, 
and  portions  are  also  liable  to  be  carried  off  in  the  slag. 

Fire  assays  of  lead  ores,  when  compared  with  the  re- 
sults obtained  by  humid  analysis,  generally  show  a  loss 
varying  from  5  to  12  per  cent.  The  fire  assay,  however, 
represents  what  is  produced  by  smelting  lead  ores  on  a 
large  scale,  and  it  is  therefore  of  great  commercial  use. 

Class  A. — Take  of  the  finely  crushed  ore  2  grains,  and 
mix  with  3  grains  dry  carbonate  of  soda,  O5  grain  borax 
glass,  0*5  grain  powdered  charcoal,  and  1  grain  cyanide 
of  potassium.  In  the  small  crucible  (similar  to  what  is 
used  in  the  Silver  Assay,  p.  121)  place  two  small  pieces  of 
wrought  iron  about  the  thickness  and  length  of  a  small 
steel  pen,  and  then  pour  in  the  assay;  cover  the  assay  with 
about  4  grains  of  common  salt,  but  allow  the  ends  of  the 
iron  pieces  to  project  above  the  assay  charge ;  put  on 
the  cover  of  the  charcoal  furnace,  and  screw  the  tightening 
pin ;  apply  a  K.F.  through  the  opening  made  in  the  fur- 


152      ASSAY  OF  SILVER,   GOLD,  MERCURY,  ETC.      PART  III. 

nace,  but  apply  it  at  first  in  a  downward  direction,  so  that 
the  flame  does  not  attack  the  bottom  of  the  crucible. 
After  a  few  minutes'  blowing  the  assay  commences  to  boil, 
and  the  furnace  will  be  found  to  be  at  a  good  red  heat. 
Do  not  increase  the  heat  until,  by  a  glance  through  the 
hole  in  the  top  of  the  furnace,  the  assay  is  found  to  be 
thoroughly  fused ;  then  increase  the  heat,  and  with  a  pair 
of  iron  pliers  extract  the  pieces  of  iron  one  by  one  whilst 
the  assay  is  in  a  thorough  state  of  fusion.  After  the  iron 
has  been  taken  away  allow  the  assay  to  cool  slowly. 

When  cool,  break  the  crucible  between  two  pieces  of 
paper  on  the  steel  anvil,  and  clean  the  lead  button  and 
weigh ;  examine  the  slag  with  a  lens,  and  if  any  globules 
of  lead  are  found  add  them  to  the  larger  button. 

If  numerous  small  globules  are  found  in  the  slag  the 
assay  should  be  repeated.  This  assay  only  takes  about  8 
minutes,  and  if  carefully  made  it  will  agree  closely  with 
fire  assays  made  on  a  large  scale. 

The  lead  button  frequently  contains  a  large  amount  of 
copper.  This  can  be  ascertained  by  dissolving  the  lead 
with  boracic  acid  in  a  deep  bore  on  charcoal  (see  Copper 
Assay)  and  deducting  the  weight  of  the  copper  found  from 
that  already  considered  to  be  lead. 

Lead  nearly  always  contains  silver,  also  gold  ;  therefore 
the  button  should  be  cupelled  and  treated  as  silver  lead 
(see  Silver  Assay).  It  should  also  be  tested  for  gold  (see 
Gold  Assay). 

Class  B. — Mix  the  finely  powdered  material  with  4 
grains  of  carbonate  of  soda,  and  1  grain  of  argol,  and  0*5 
grain  borax  glass 

Place  the  mixture  in  a  small  crucible,  and  after  covering 
with  from  3  to  4  grains  of  common  salt  fuse  and  treat  in 
a  similar  manner  to  Class  A. 


PART  III.  BISMUTH.  1 53 

BISMUTH. 

Bismuth  native  has  a  metallic  lustre,  the  streak,  and 
colour,  silver  white,  with  a  reddish  hue.  It  tarnishes 
readily.  It  has  a  hardness  of  2—2*5  and  specific  gravity 
=  9-72. 

Native  bismuth  occurs  in  veins  in  gneiss  and  other 
crystalline  rocks  and  in  clay  slate  accompanying  various 
ores  of  silver,  cobalt,  lead,  and  zinc. 

The  principal  ores  of  bismuth  are — 

Sulphide',  contains  bismuth  81*3  per  cent.,  sulphur 
18*7  per  cent. 

Bismuth  blende :  contains  oxide  of  bismuth  58*8  per 
cent.,  and  is  mixed  with  silica,  arsenic,  and  small 
proportions  of  copper,  iron,  and  cobalt. 

Acicular  bismuth :  contains  from  34  to  37  per  cent, 
bismuth,  combined  with  sulphur,  copper,  and  lead. 

Carbonate  of  bismuth :  contains  about  89*75  per  cent, 
oxide  of  bismuth,  combined  with  carbon  dioxide  and  water. 

Bismuth  has  also  been  found  combined  with  tellurium, 
and  exists  in  about  the  following  proportions :  bismuth 
52  per  cent.,  and  tellurium  48  per  cent. 

The  carbonates  and  oxides  of  bismuth,  when  mixed  with 
their  gangue,  resemble  in  appearance  some  lead  ores ;  and, 
as  the  assay  is  conducted  in  a  similar  manner,  it  often 
happens  that  until  the  button  is  examined  for  malleability, 
the  difference  is  not  discovered.  Bismuth  forms  a  brittle 
and  coarsely  crystalline  button,  having  a  bright  fracture, 
which  will  not  bear  hammering  on  the  anvil  without 
breaking  up  into  fragments,  whilst  lead  is  ductile  and 
malleable. 

The  button,  if  pure,  possesses,  when  fractured,  a  fine 
reddish  colour. 

If  arsenic  is  present  the  button  appears  of  a  white  colour. 


154      ASSAY   OF  SILVER,   GOLD,   MERCURY,   ETC.      PART  III. 

Copper  does  not  alloy  with  bismuth,  but  its  presence 
can  be  detected  by  using  a  magnifying  glass.  When  copper 
is  present  it  will  be  found  to  be  mixed  and  not  alloyed. 

Antimony  gives  the  button  a  dull  appearance,  and  the 
crystals  are  much  finer. 

Sulphur  blackens  bismuth. 

Lead,  when  present,  does  not  prevent  bismuth  from 
forming  large  crystals,  but  it  is  detected  by  the  large 
crystals  being  studded  all  over  with  fine  crystals 


Before  making  a  determinative  assay  it  is  best  to  make 
a  qualitative  examination  by  taking  about  1  ^  grain  of  the 
crushed  ore  or  product  and  roasting  at  a  gentle  heat  with 
powdered  charcoal  in  a  similar  manner  to  the  copper  assay 
(see  p.  147). 

Then  mix  with  1^  grain  soda,  1^  grain  carbonate  of 
potash,  Oo  grain  borax  glass,  and  a  very  small  quantity  of 
powdered  charcoal.  Place  in  the  crucible  two  small  pieces  of 
metallic  iron,  add  the  assay  charge,  and  cover  with  a  thin 
layer  of  salt,  and  fuse  according  to  directions  given  in  the 
Lead  Assay  (p.  151).  The  difficulty  in  making  the  bismuth 
assay  by  this  method  is  to  obtain  all  the  small  shots  of  metal 
in  one  globule.  It  is  seldom  done,  but  the  button  or  buttons 
which  are  formed  can  be  separated  from  the  flux  and 
examined  by  hammering  on  the  anvil,  when  the  appearance 
of  the  fracture  will,  as  described  above,  indicate  the  pre- 
sence of  other  metals. 

To  collect  bismuth  in  one  button  an  addition  of  some 
other  metal  is  necessary.  Pure  silver  is  considered  the 
best  and  is  generally  employed. 

The  ores  and  products  of  bismuth  are  assayed  in  the 
following  way : — 

Take   1J  grain  of  the    finely   powdered  mineral  and 


PART  III.  BISMUTH.  155 

roast  on  a  small  clay  capsule  in  a  similar  manner  to  the 
copper  assay.  The  heat  required  is  not  so  great  as  that 
necessary  in  roasting  copper  ores,  as  bismuth  is  readily 
fusible  and  sinters  if  the  heat  applied  is  too  great. 

After  roasting,  mix  the  assay  with  2  grains  of  finely  pre- 
cipitated pure  silver,  with  1^  grain  soda,  1^  grain  car- 
bonate of  potash,  0-5  grain  borax  glass,  a  small  quantity 
of  powdered  charcoal,  and  place  in  the  small  crucible,  in 
which  two  or  three  small  pieces  of  iron  have  been  pre- 
viously placed ;  cover  with  a  thin  layer  of  salt  and  fuse  as 
before  directed.  The  button  obtained  consists  of  an  alloy 
of  silver  and  bismuth,  but  it  is  seldom  clean  enough  to 
weigh  without  further  treatment. 

The  button  should  be  fused  for  a  few  moments  on 
charcoal  with  a  little  borax  glass.  The  flame  employed 
must  be  a  very  mild  K.F.,  as  bismuth  volatilises  at  a  low 
temperature.  When  the  surface  of  the  assay  becomes 
bright,  stop  blowing,  allow  it  to  cool,  and  then  clean  the 
button  by  brushing  it. 

Weigh,  and  deduct  the  weight  of  the  silver  previously 
added  from  the  total  found ;  the  remainder  should  be 
bismuth. 

Bismuth  ores  and  products  are  generally  associated 
with  silver,  and  to  ensure  the  assay  being  correct  the 
author  always  makes  a  separate  assay  for  silver  by  fusing 
1 J  grain  of  the  mineral  (see  Silver  Assay),  and  if  any 
silver  is  present  its  weight -is  deducted  from  the  button 
of  bismuth  silver  found  in  the  bismuth  assay. 

No  fire  assay  of  bismuth  ores  or  products  gives  analytic- 
ally accurate  results.  The  blowpipe  assay  is  made  in  less 
than  half  an  hour,  and  is  sufficiently  accurate  to  guide 
the  explorer  or  metallurgist  in  his  practical  estimation  or 
treatment  of  the  ores  or  products. 


156      ASSAY   OF  SILVER,   GOLD,   MERCURY,   ETC.      PART  III. 

TIN. 

Tin  in  a  metallic  state  is  probably  only  an  artificial  pro- 
duct. 

J.  A.  Phillips  states  that  tin  has  more  than  almost  any 
other  metal  a  characteristic  mode  of  occurrence,  being  in- 
variably found  in  the  older  crystalline  and  metamorphic 
rocks.  This  opinion  is  confirmed  by  Dana  and  others,  and 
the  author  has  observed  the  same  peculiarity  in  the  dis- 
tribution of  tin  ores. 

Metallic  tin  is  a  white  metal  with  a  lustre  closely 
approaching  that  of  silver  and  with  a  specific  gravity  of 
7*29.  It  is  easily  distinguished  from  any  other  metal  by 
the  peculiar  '  tin  odour  '  which  it  gives  to  the  hand  or  finger 
after  it  has  been  rubbed  for  a  few  moments. 

The  principal  ore  of  tin  is  cassiterite,  containing  78*62 
tin  and  oxygen  21*38. 

Tin  has  been  found  combined  with  sulphides  of  copper, 
iron,  and  zinc  in  Cornwall,  in  stannite,  but  the  tin  obtained 
was  only  26  per  cent. 

The  pure  oxides  of  tin  are  readily  assayed  by  a  gentle 
fusion  with  a  reducing  flux  in  a  small  crucible  before  the 
blowpipe,  when  a  pure  metallic  button  is  obtained ;  but,  as 
many  tin  ores  are  combined  with  an  excess  of  silica  as 
well  as  some  sulphur,  arsenic,  and  tungsten,  it  is  necessary 
to  subject  them  to  a  preparatory  treatment  before  fusing 
them  in  a  crucible  with  a  reducing  flux. 

Assay. 
The  tin  assay  is  divided  into  four  classes — 

Class  A. 

Pure  oxides  of  tin. 
Class  B. 

Tin  ores  containing  silica,  also  tin  slags. 


PART  III.  TIN.  157 

Class  C. 

Tin  ores  containing  arsenic,  sulphur,  and  tungsten. 

Class  D. 

Ores  containing  under  5  per  cent,  of  tin. 

Class  A. — Weigh  out  1J  grain  of  the  oxide,  and  in- 
timately mix  with  10  grains  of  cyanide  of  potassium 
and  1  grain  of  soda.  Place  the  mixture  in  a  crucible  in 
the  bottom  of  which  has  been  previously  placed  and 
pressed  down  a  small  quantity  of  cyanide  of  potassium. 

Eemove  the  crucible  to  the  charcoal  furnace  and  fuse 
with  a  gentle  heat.  The  time  required  to  finish  the  assay 
is  seldom  more  than  6  to  7  minutes.  The  assay  can  be 
watched,  and  the  completion  of  the  fusion  ascertained  by 
looking  through  the  hole  in  the  top  of  the  furnace.  When 
cold,  break  the  crucible.  The  button  should  be  of  a 
silvery  white  colour.  Dissolve  the  flux  in  warm  water,  and 
look  carefully  for  any  small  shots  of  tin  that  may  be  present. 
If  any  are  found  they  should  be  cleaned  and  then  weighed 
with  the  large  button. 

The  cyanide  of  potassium  used  for  blowpipe  assaying 
being  pure,  soda  is  added  to  secure  the  perfect  fusion  of 
any  small  quantities  of  silica  or  other  impurities  which 
generally  accompany  tin  oxides. 

The  button  of  tin  obtained  should  be  rolled  or  hammered 
out,  and  then  tested  to  see  if  it  contains  any  lead  or  copper. 

The  above-described  method,  if  carefully  followed, 
affords  accurate  results. 

Class  B. — Silica  being  injurious  to  the  extraction  of 
tin  by  fusion,  the  ore  to  be  examined  should  be  first 
crushed  up  fine. 

Take  from  1  to  20  oz.  of  the  crushed  ore,  according 
to  its  richness,  and  van  carefully  in  the  batea. 

Tin  oxides  have  a  specific  gravity  of  about  7,  and 
silica  only  a  specific  gravity  of  about  2 -7 ;  therefore 


158      ASSAY   OF  SILVER,   GOLD,  MERCURY,   ETC.      PAIIT  III. 

the  operator,  by  careful  washing,  can  with  safety  separate 
the  silica  from  the  tin  ore,  or  tin  stone,  as  it  is  generally 
termed. 

Eemove  the  concentrated  ore  from  the  batea  to  a  small 
porcelain  dish  and  carefully  dry ;  then  weigh  ;  after  weigh- 
ing grind  in  the  agate  mortar  and  thoroughly  mix.  Then 
weigh  out  1  ^  grain  of  the  concentrated  ore  and  proceed 
to  melt,  and  determine  as  in  Class  A. 

The  percentage  of  tin  in  the  original  sample  treated 
is  ascertained  by  first  noting  the  quantity  weighed  out 
for  vanning,  then  noting  the  quantity  of  concentrated  ore 
obtained,  and  then  the  amount  of  pure  metallic  tin  ex- 
tracted from  1 1  grain  of  the  concentrated  ore. 

Sometimes  the  tin  ores  cannot  be  washed  down  closely 
without  a  loss  of  tin ;  in  such  a  case  concentrate  the  ore 
as  much  as  possible  by  washing,  then  dry  and  weigh. 

Take  1^  grain  of  the  concentrations  and  boil  with 
hydrochloric  acid  in  a  platinum  dish  or  porcelain  capsule 
over  the  spirit  lamp.  The  assay  being  finely  powdered, 
the  silica  is  dissolved.  Tin  oxide  is  insoluble  in  hydro- 
chloric acid. 

The  dissolved  silica  is  decanted  off;  the  tin  oxide  is 
washed  with  a  small  quantity  of  water,  then  dried,  and 
fused  as  in  Class  A. 

Class  C. — The  removal  of  sulphur,  arsenic,  and  tungsten 
from  tin  is  necessary  before  tin  can  be  extracted  in  a  pure 
state  from  its  ores  by  the  blowpipe. 

Take  from  3  to  10  grains,  according  to  the  quality,  of 
the  finely  powdered  ore,  and  place  it  in  a  small  flask ;  add 
a  small  quantity  of  nitro-hydrochloric  acid  (made  up  of  3 
parts  of  hydrochloric  to  1  part  of  nitric  acid).  Boil 
until  the  greater  part  of  the  mixed  acids  has  evapo- 
rated. Allow  the  flask  to  cool,  add  water,  settle,  and 
decant,  and  so  on  until  the  water  is  free  from  acid.  The 


PART  III.  TIN.  159 

insoluble  residue  consists  of  tin  oxide,  tungsten,  and  a 
little  silica.  Add  a  small  quantity  of  caustic  ammonia 
solution  to  the  residue,  and  allow  it  to  boil  in  the  flask  for 
about  an  hour  ;  then  decant  and  van  the  residue  to  remove 
the  silica. 

Dry  the  tin  oxide  and  proceed  to  finish  the  assay  accord- 
ing to  the  method  adopted  in  Class  A. 

Class  D. — Many  ores  of  tin  contain  less  than  5  per  cent, 
of  metallic  tin. 

To  arrive  at  a  correct  assay  of  such  ores  it  is  necessary 
to  treat  a  large  quantity.  Take  about  5  Ibs.  in  weight  of 
the  finely  crushed  ore  and  van  carefully  in  the  batea,  and 
afterwards  treat  according  to  the  directions  given  in  Classes 
A,  B,  and  C. 

IRON. 

Native  iron  is  rare.  It  has  a  hardness  4-5  and  specific 
gravity=  7*3-7*8,  with  a  metallic  lustre  and  an  iron-grey 
colour,  also  a  streak  shining.  It  is  malleable,  but  has  a 
hackly  fracture  and  is  strongly  attracted  by  the  magnet. 
Native  iron  must  be  considered  only  as  a  mineralogical 
curiosity,  as  it  has  rarely  been  found.  Nearly  all  inorganic 
as  well  as  organic  substances  that  exist  in  nature  con- 
tain more  or  less  iron. 

The  principal  ores  from  which  iron  is  manufactured 
are  those  in  which  the  iron  is  combined  with  oxygen  and 
carbon,  as  oxides  and  carbonates. 

Sulphides  of  iron  are  disseminated  all  over  the  globe, 
but  they  are  rarely  converted  into  metallic  iron.  Magnetic 
iron  ore  contains  about  72*41  per  cent,  iron ;  the  re- 
mainder is  oxygen.  Specular  and  red  hematite  ore  contain 
about  70  per  cent,  iron  and  30  per  cent,  oxygen. 

Brown  iron  ore,  or  brown  hematite,  contains  about 
59*90  per  cent,  iron,  and  the  rest  consists  of  oxygen  and 
water. 


160      ASSAY   OF  SILVER,  GOLD,   MERCURY,   ETC.      PART  III. 

Carbonate  of  iron,  or  spathic  iron,  contains  48'22  per 
cent,  iron,  and  the  remainder  carbon  and  oxygen. 

Menaccanite  (ilmenite),  a  titanic  iron  ore,  varies  in  its 
composition ;  it  contains  about  36  per  cent,  of  iron  on 
the  average. 

Franklinite  contains  about  45*16  per  cent,  of  iron, 
and  the  remainder  is  made  up  of  zinc,  manganese,  and 
oxygen. 

The  assay  of  iron  ores  scarcely  comes  under  the  head 
of  the  blowpipe  fire  assay,  as  the  most  accurate  as  well  as 
expeditious  method  of  ascertaining  the  percentage  of 
iron  in  a  sample  of  ore  is  nearly  all  done  by  the  humid 
process. 

The  reagents  and  apparatus  required  for  the  iron 
quantitative  determination  are  necessary  adjuncts  to  the 
blowpipe  outfit;  therefore,  instead  of  using  a  tedious 
and  a  very  unreliable  method  of  extracting  metallic  iron 
by  fire  from  its  ores,  the  following  plan  has  been  adopted, 
as  it  affords  correct  results. 

Assay. 

Crush  the  iron  ore  in  the  steel  mortar,  and  then  grind 
to  the  finest  possible  powder  in  the  agate  mortar. 

Weigh  out  1J  grain  of  the  finely  powdered  ore,  and 
place  the  same  in  a  small  test  tube  ;  add  a  little  hydrochloric 
acid.  If  the  assay  effervesces  the  ore  is  a  carbonate,  and 
the  acid  must  be  added  little  by  little  to  avoid  the  loss  of 
a  portion  of  the  assay  ;  but  if  effervescence  does  not  take 
place  the  acid  can  be  poured  over  the  assay  at  once.  Heat 
the  assay  contained  in  the  test  tube  over  the  spirit  lamp 
until  everything  is  in  solution  that  the  hydrochloric  acid 
will  take  up.  Then  add  a  few  drops  of  nitric  acid  and 
again  boil  the  assay  over  the  spirit  lamp. 


PART  III.  IRON.  161 

The  assay  having  been  thoroughly  boiled,  is  allowed  to 
cool,  and  the  solution  is  diluted  with  distilled  water. 

If,  on  dilution,  any  sediment  is  found,  it  must  be  sepa- 
rated by  nitration,  and  the  filter  must  be  examined  with 
great  care  in  regard  to  colour.  If  white,  the  sediment 
contains  no  iron.  If  red,  yellowish,  or  grey,  it  contains 
undissolved  iron,  and  it  must  be  treated  by  carefully 
drying  it  on  a  procelain  dish  over  the  lamp.  When  dry, 
mix  it  with  3  times  its  volume  of  soda  and  an  equal 
part  of  borax  glass ;  wrap  the  mixture  in  a  soda-paper 
cornet,  and  fuse  it  on  charcoal  in  a  deep  bore  with  an  O.F. 
until  the  mass  is  thoroughly  fused  and  transparent. 

When  the  fused  mass  is  cold,  remove  it  to  the  steel 
mortar  and  crush.  After  crushing,  boil  with  HC1  in  a  small 
porcelain  dish,  and  add  a  few  drops  of  nitric  acid  before 
the  boiling  is  stopped,  and  heat  slightly  for  a  few  moments 
to  allow  oxidation  to  take  place.  The  solution  is  then 
slowly  evaporated  to  dryness  over  the  lamp.  A  few  drops 
of  HC1  are  added  to  the  dry  mass,  and  then  some  distilled 
water,  and  it  is  again  warmed  over  the  lamp. 

After  warming  filter,  and  add  the  filtrate  to  the  first  solu- 
tion. The  residue,  collected  on  the  filter,  should  be  silica. 

Add  a  few  drops  of  sulphuric  acid  to  the  solution  and  stir. 
If  anything  like  a  white  precipitate  is  seen  baryta  is  present, 
and  the  solution  must  be  allowed  to  settle.  The  sulphate  of 
baryta  is  separated  from  the  iron  solution  by  filtering. 

If  the  iron  ores  are  pure,  the  troublesome  operations  of 
dissolving  the  sediment  and  separating  the  baryta,  &c.,  are 
dispensed  with,  and  the  assay  is  quickly  finished.  Add 
ammonia  to  the  iron  solution.  Iron  and  alumina  are 
both  thrown  down  together  by  the  above  alkaline  pre- 
cipitant. To  obtain  an  oxide  of  iron  sufficiently  pure  to 
weigh,  it  is  always  necessary  to  separate  alumina  from 
the  iron  oxide. 

M 


162      ASSAY   OF  SILVER,   GOLD,   MERCURY,  ETC.     PART   III. 

Alumina  is  separated  from  the  iron  oxides  by  attack- 
ing the  moist  precipitate  with  caustic  potash ;  the  latter 
dissolves  the  alumina,  leaving  the  iron  oxide. 

The  assay  is  now  proceeded  with  by  drying  the  pre- 
cipitate of  iron  oxides  and  alumina  remaining  on  the  filter 
paper. 

Before  the  paper  becomes  quite  dry  remove  the  precipi- 
tate from  the  filter  paper  with  a  spatula  or  small  knife. 
The  filter  paper  should  be  placed  in  a  porcelain  dish 
with  a  little  HC1  and  washed  with  a  little  warm  water, 
and  this  solution  added  to  the  main  precipitate.  In  a  small 
beaker  or  large  test  tube  boil  the  iron  and  alumina  pre- 
cipitate with  a  strong  solution  of  caustic  potash. 

Then  dilute  with  water  and  collect  the  sesquioxide  of 
iron  on  a  filter.  Warm  the  filter  containing  the  precipitate, 
and  when  the  filter  is  nearly  dry  remove  the  iron  oxide 
from  the  filter  to  a  porcelain  capsule.  Burn  the  filter 
paper  by  the  blowpipe  over  a  porcelain  or  platinum  dish, 
and  add  the  ash  and  what  iron  oxide  it  contains  to  the 
main  precipitate.  Dry  the  precipitate  and  apply  a  good 
red  heat  to  the  capsule  containing  it. 

The  iron  oxide  is  now  weighed,  and  after  deducting 
the  weight  of  the  ash  contained  in  the  filter  paper  the 
metallic  iron  may,  according  to  Plattner,  be  estimated  as 
follows: — 

6 100  parts  of  the  sesquioxide  of  iron  correspond  almost 
exactly  to  70  parts  of  metallic  iron ;  so  that  it  may  be 
conveniently  calculated  as  70  parts.  If  the  percentage  of 
raw  iron  which  a  dry  assay  in  a  charcoal  crucible  would  give 
is  required,  it  may  be  easily,  calculated  by  assuming  the 
raw  iron  from  the  crucible  to  contain  on  an  average,  in 
100  parts,  96  parts  of  iron  and  4  parts  of  carbon.' 

The  above-described  method  of  assaying  iron  ores 
affords  accurate  results,  and  when  such  a  small  quantity 


PART  III.  NICKEL.  163 

as  1^  grain  is  operated  upon  the  assay  can  be  completed 
in  about  30  minutes  and  a  correct  report  given. 

NICKEL. 

Nickel  ores  have  generally  a  pale  colour  and  a 
metallic  lustre. 

The  principal  ores  of  nickel  are  : — 

Copper  nickel  (kupfernickel)  has  a  specific  gravity  of 
7*3  to  7*5,  and  consists  of  44  per  cent,  of  nickel  and  56 
per  cent,  of  arsenic. 

White  nickel,  an  arsenical  ore,  contains  from  20  to  30 
per  cent,  of  nickel. 

Nickel  glance  is  an  arsenical  ore,  but  contains  sulphur. 
It  carries  from  20  to  38  per  cent,  of  nickel. 

Antimonial  nickel  contains  about  29  per  cent,  of  nickel 
and  no  sulphur. 

Millerite  is  a  brass-yellow  sulphide  of  nickel,  containing 
64  per  cent,  of  nickel. 

Pentlandite  is  a  double  sulphide  of  iron  and  nickel, 
and  contains  from  10  to  21  per  cent,  of  nickel. 

Assay. 

The  assay  for  nickel  alone  will  be  confined  to  the  ore 
called  kupfernickel,  and  the  remaining  varieties  will  be 
treated  fully  under  the  head  of  'Nickel  and  Cobalt.' 

Kupfernickel,  when  pure,  consists  of  arsenic  55- 93, 
nickel  44-07,  but  it  generally  contains  about  1  per  cent, 
of  foreign  matter,  such  as  iron,  cobalt,  lead,  and  sulphur. 

Take  1  grain  of  the  finely  powdered  ore  and  mix 
with  £  grain  of  borax  glass,  and  fuse  on  charcoal  with 
the  E.F.  After  the  assay  is  in  a  state  of  fusion  treat  it 
with  the  outer  point  of  the  O.F.  until  the  arseniate  of 
nickel  commences  to  oxidise ;  then  dip  the  globule  and  slag 
whilst  still  hot  in  water,  to  separate  the  slag,  which  is  easily 

M   2 


164      ASSAY  OF  SILVER,   GOLD,   MERCURY,   ETC.      PART  III. 

done  with  the  fingers ;  then  heat  the  globule  in  a  deep 
bore  (in  charcoal)  with  a  weak  K.F.,  keeping  it  in  fusion 
with  a  bright  surface  until  all  excess  of  arsenic  is  vola- 
tilised. The  globule  that  remains  will  weigh  about  0*71 
grain,  and  is  JN"i4As,  which  contains  arsenic  38-825  and 
nickel  61-175,  and  the  impurities  present  account  for 
the  loss. 

Care  must  be  taken  not  to  use  an  excess  of  borax  glass, 
as  sufficient  surface  would  not  be  exposed  for  oxidation. 

COBALT. 

Cobalt  ores  generally  have  a  tin-white  to  steel-grey 
colour.  The  principal  ores  : — 

Smcdtine  has  a  specific  gravity  of  6*4  to  7*2,  and  con- 
tains from  3  to  14  per  cent,  of  cobalt,  with  from  60  to  75 
per  cent,  of  arsenic;  the  remainder  is  generally  nickel  and 
iron,  with  sometimes  a  trace  of  copper. 

Cobaltitd,  or  glance  cobalt,  has  a  specific  gravity  of  6 
to  6-3,  and  contains  about  35*5  per  cent,  of  cobalt,  with 
sulphur  19-3  and  arsenic  45*2.  The  cobalt  is  sometimes 
largely  replaced  by  iron  and  sparingly  by  copper. 

Erytkrite  (cobalt  bloom)  has  a  pinkish  purple  colour, 
resembling  that  of  a  peach  blossom,  and  when  scratched  it 
affords  a  greenish  streak.  It  is  composed  of  about  39  per 
cent,  of  cobalt  oxide,  of  37  per  cent,  of  arsenic  anhydride, 
and  22  per  cent,  of  water. 

Cobalt  sometimes  is  found  in  mispickel  (arsenic 
pyrites). 

Assay. 

A  full  description  of  the  assay  of  the  ores  of  cobalt 
will  be  described  under  the  head  of  'Nickel  and  Cobalt,' 
and  only  one  variety  of  cobalt  ore  will  be  treated  separately 
for  cobalt. 


PART  III.  COBALT.  165 

Skutterudite  contains,  when  pure,  arsenic  79*26  and 
cobalt  20-74,  with  the  occasional  replacement  of  about  2 
per  cent,  of  the  cobalt  by  some  nickel  and  iron. 

Take  1  grain  of  the  crushed  ore  and  mix  with  0-5 
grain  of  soda  and  0-15  grain  of  borax  glass  in  a  soda- 
paper  cornet,  and  treat  on  charcoal  with  a  K.F.  until  all 
the  metallic  particles  are  united  in  one  globule.  By  this 
means  the  small  quantity  of  iron  present  is  slagged  and 
the  greater  part  of  the  arsenic  volatilised.  If  sulphur  is 
present  it  unites  with  the  flux,  but  causes  the  latter  to 
become  in  a  great  part  absorbed  in  the  charcoal. 

If  the  metallic  globule  be  now  freed  from  adhering 
slag,  and  be  heated  in  a  deep  bore  in  charcoal  with  a  E.F., 
and  kept  fluid  until  no  more  arsenic  volatilises,  the  globule 
left  will  weigh  about  0*33  grain. 

The  R.F.  must  be  only  strong  enough  to  keep  the 
metal  fluid  with  a  bright  surface.  If  too  violent  a  flame 
is  applied  the  assay  will  boil  and  spurt,  causing  a  mecha- 
nical loss. 

The  globule  now  consists  of  cobalt  61' 131,  and  arsenic 
38-869. 

NICKEL  AND  COBALT  ASSAYS. 

Plattner's  method  of  conducting  the  above  assay  is 
the  one  chiefly  adopted  in  this  work,  but  with  many 
modifications. 

As  cobalt  and  nickel  cannot  be  separated  from  their 
compounds  in  the  metallic  state  by  fusion,  like  silver, 
gold,  lead,  &c.,  they  are  separated  by  combining  them 
with  arsenic. 

The  mixed  combination  of  nickel,  cobalt,  and  arsenic 
is  weighed ;  the  arsenide  of  cobalt  is  then  slagged  off, 
leaving  an  arsenide  of  nickel,  which  can  be  weighed  as 
such,  and  the  amount  of  metallic  nickel  calculated  from 


166      ASSAY   OF  SILVER,   GOLD,   MERCURY,   ETC.      PART  III. 

it.  The  percentage  of  cobalt  is  estimated  from  the  differ- 
ence in  weight  between  the  mixed  arsenides  and  that  of 
the  arsenide  of  nickel  found.  The  assay  is  not  only  easy 
but  accurate.  The  assay  has  been  divided  into  two  classes, 
called  A  and  B. 

Class  A. 

Consists  of  all  nickel  and  cobalt  ores  and  products  which  are 
not  combined  with  arsenic. 

Class  B. 

Consists  of  all  nickel  and  cobalt  ores  and  products  which  are 
in  combination  with  arsenic. 

Class  A  (a). — If  nickel  and  cobalt  compounds  are  not 
in  the  state  of  arsenides  they  require  to  be  made  so  and 
then  fused  to  form  a  button  of  metallic  arsenides  before 
they  can  be  estimated  quantitatively  by  the  blowpipe ; 
therefore  Class  A  treats  of  the  arsenides  solely. 

Take  H  grain  of  the  ore  or  product,  and  if  any  sul- 
phides are  present  roast  according  to  directions  given  in 
Copper  Assay  (p.  147).  Finish  the  roasting  (when  all 
odour  has  ceased  to  be  evolved)  by  an  addition  of  1  grain 
of  carbonate  of  ammonia,  which  must  be  previously  tritu- 
rated with  the  assay  in  the  agate  mortar. 

If  sulphur  is  absent  the  roasting  is  dispensed  with. 

Take  the  oxidised  assay  and  mix  it  with  1  to  2  grains 
of  metallic  arsenic  in  a  small  clay  crucible;  place  the 
crucible  in  the  charcoal  furnace  on  an  iron  wire  ring, 
and  fuse  at  a  mild  heat.  It  is  generally  advisable 
to  cover  the  crucible  with  a  clay  capsule.  This  assay 
should  be  conducted  outside,  as  the  arsenical  fumes 
are  poisonous  in  a  room.  The  contents  of  the  crucible 
are  carefully  detached,  and  are  then  treated  according  to 
'Class  B. 

If  the  arsenicising  must  be  done  in  the  room,  take  0*75 


PART  III.  NICKEL  AND   COBALT  ASSAYS.  167 

grain  of  the  nickel  and  cobalt  oxides  and  mix  with  1*5 
grain  powdered  metallic  arsenic,  and  wrap  in  a  small  soda- 
paper  cornet.  Place  the  assay  in  the  bottom  of  a  small 
tube  closed  at  one  end. 

Place  in  the  mouth  of  the  tube  a  small  roll  of  dry 
filter  paper,  to  absorb  the  moisture  evolved  from  the 
charred  soda  paper.  Heat  the  assay  gradually  over  the 
spirit  lamp  to  redness. 

Turn  the  tube  every  now  and  then,  to  prevent  the 
charred  paper  adhering  to  the  sides  of  the  tube.  Con- 
tinue the  heat  until  no  more  sublimate  of  arsenic  is  found 
on  the  inside  of  the  tube. 

Cut  off  the  lower  portion  of  the  tube  (by  using  a  file) 
containing  the  assay,  and  remove  carefully. 

The  assay  is  now  treated  as  Class  B.  If  the  oxide 
consists  chiefly  of  protoxide  of  nickel  and  oxides  of  cobalt 
in  which  the  former  prevails,  the  resulting  arsenides  can 
easily  be  melted  to  one  button  during  the  fusion  in  the 
crucible ;  if,  however,  oxide  of  cobalt  prevails,  the  result- 
ing arsenides  melt  with  difficulty,  and  about  0-25  grain 
of  iron  filings  must  be  added,  so  as  to  form  arsenide  of 
iron,  which  produces  a  fusible  combination  with  the 
arsenide  of  cobalt  in  the  subsequent  fusion. 

Class  B  (a)  consists  of  nickel  and  cobalt,  combined 
with  arsenic  and  some  iron. 

Take  1^  grain  of  the  finely  powdered  mineral,  and 
mix  on  the  agate  mortar  with  0*8  grain  soda,  0*20  grain 
borax  glass.  Place  a  soda-paper  cornet  in  a  deep  bore  in 
charcoal,  and  fuse  with  a  moderate  E.F.  until  the  flux  has 
become  a  slag  and  the  metallic  particles  have  united  to  a 
button.  Cool  the  button  in  water  to  remove  the  slag* 
Fuse  the  button  on  a  cavity  in  charcoal  with  a  mild  E.F. 
until  the  button  shows  a  bright  surface  and  assumes  a 
rotary  motion.  The  iron  has  then  been  slagged  off.  Con- 


168      ASSAY   OF  SILVER,   GOLD,  MERCURY,   ETC.      PART  III. 

tinue  to  keep  the  button  in  fusion  until  all  fumes  of 
arsenic  have  ceased  to  be  evolved. 

Allow  the  button  to  cool,  and  weigh  ;  the  weight  gives 
the  sum  of  (CoNi)4As. 

The  amount  of  metal  in  the  weighed  arsenides  is  as 
follows : — 

Co4As          .         .     61 '5  percent,  cobalt. 
Ni4As          .         .     607        „        nickel. 

Sometimes  it  is  difficult  to  slag  off  the  last  traces  of 
the  iron ;  in  such  a  case  add  a  little  borax  glass,  and  fuse 
until  the  button  shows  a  perfectly  bright  surface. 

The  button  having  been  weighed,  the  cobalt  is  next 
slagged  off  by  fusing  with  a  moderate  E.F.  in  a  cavity  on 
charcoal,  a  small  quantity  of  borax  glass  having  been  pre- 
viously added. 

Cobalt  separates  slowly,  and  until  it  is  all  gone  the 
solidified  button  is  always  covered  with  a  black  crust  of 
oxide.  The  brightening  of  the  button  continues  on  add- 
ing fresh  borax  so  long  as  the  arsenide  of  cobalt  is  present ; 
but  when  all  of  the  cobalt  is  separated,  and  the  arsenide 
of  nickel  begins  to  oxidise,  a  film  of  basic  arseniate  of 
nickel  forms,  which  moves  slowly  about  the  surface. 

If  the  blast  is  stopped  as  soon  as  the  phenomenon 
above  described  can  be  distinctly  perceived,  and  a  part  of 
the  glass  immediately  pinched  out  and  slowly  raised,  re- 
maining still  connected  with  the  main  portion,  it  appears 
generally  rather  violet  than  blue  against  the  daylight, 
provided  it  is  not  too  strongly  coloured  with  cobalt. 

If  all  the  cobalt  had  been  separated  the  glass  would 
only  appear  pale  brown.  On  the  surface  of  the  remain- 
ing arsenide  of  nickel  beside  the  purple  glass  is  seen  an 
apple-green  film  of  basic  arseniate  of  nickel,  which  indicates 
that  only  Ni4As  remains. 


PART  III.  NICKEL  AND   COBALT  ASSAYS.  169 

The  Co4As  is  completely  slagged  off,  while  the  Ni4As 
retains  none  of  the  arsenic  from  it,  and  therefore  both 
metals  can  be  quantitatively  determined  in  the  compounds. 

If  proper  care  is  taken  in  making  the  above  assay  the 
loss  of  nickel  (even  if  a  large  film  is  observed  on  the  sur- 
face of  the  assay)  is  so  small  that  it  can  scarcely  be  de- 
termined on  the  fine  assay  balance. 

Class  B  (6)  consists  of  ores  and  products  in  which 
nickel,  cobalt,  copper,  and  iron  are  combined  with  a  small 
quantity  of  arsenic. 

Take  1 J  grain  for  assay  and  treat  in  a  similar  manner 
to  Class  A.  After  the  cobalt  has  been  slagged  off  any 
copper  that  is  present  will  be  found  combined  with  the 
nickel  compound  as 

Ni4As  and  Co6As. 

If  the  amount  of  copper  present  exceeds  that  of  nickel 
it  must  be  treated  by  the  humid  method.  After  weigh- 
ing the  button  of  nickel,  copper,  and  arsenic,  add  1  grain 
of  pure  gold,  and  fuse  with  a  moderate  heat  on  a  cavity 
on  charcoal  with  a  small  quantity  of  salt  of  phosphorus. 

Allow  air  to  get  access  to  the  button.  Arsenide  of 
nickel  soon  dissolves  in  the  glass,  making  the  glass  a  pure 
yellow  colour. 

When  the  salt  has  become  saturated,  cool  the  button 
in  water,  remove  the  slag,  and  again  fuse  with  a  fresh 
portion  of  the  salt,  and  treat  until  its  surface  ceases  to  be 
covered  with  a  film  of  oxide  and  begins  to  show  a  bluish 
green  colour.  Cool  the  button  in  water,  and  then  separate 
the  last  portions  of  arsenide  of  nickel  by  fusing  as  usual 
with  a  little  borax  on  charcoal. 

If  the  cupriferous  gold  button  shows  a  clean,  metallic, 
lustrous  surface,  and  does  not  crack  wh^n  beaten  out  cold, 


170      ASSAY   OF  SILVER,   GOLD,   MERCURY,   ETC.     PART  III. 

it  is  weighed,  and  the  copper  determined  from  the  in- 
crease in  weight. 

Arsenide  of  copper  has  the  following  composition : — 

Cu6As         .         .     71 '7  per  cent,  copper. 
28-3         „        arsenic. 

Class  B  (c)  consists  of  arsenides  of  nickel,  cobalt,  iron, 
copper,  also  brass  and  products  containing  lead,  bismuth, 
zinc,  sulphur,  and  earthy  matters. 

1£  grain  of  the  finely  powdered  mineral  is  roasted 
according  to  directions  given  in  Class  A,  and  also  after- 
wards arsenicised  as  there  directed. 

Mix  the  assay  with  3  grains  soda,  2  grains  potash,  and 
0*5  grain  borax  glass.  Add  1  grain  pure  silver.  Place 
the  mixture  in  the  clay  crucible,  in  which  a  small  piece  of 
iron  has  been  added,  cover  with  a  thin  layer  of  salt,  and, 
after  covering  with  a  clay  cup,  fuse  as  directed  in  the 
Lead  Assay  (p.  151). 

The  heat  must  be  sharp  towards  the  end,  to  collect  the 
arsenide  in  one  button. 

In  five  or  six  minutes  the  arsenides  collect  in  a  round 
button  at  the  bottom,  and  the  earthy  matters  and  oxides, 
which  do  not  separate  in  the  metallic  state,  are  completely 
slagged  off.  The  iron  passes  into  the  metallic  arsenides^ 
and  the  lead  or  bismuth  passes  into  an  alloy  with  the 
silver,  which  unites  with  the  arsenides  in  one  button,  but 
which  can  be  easily  mechanically  separated.  The 
quantity  of  lead  or  bismuth  present  can  be  estimated  by 
first  weighing  the  alloy  and  then  cupelling  it,  when  the 
loss  will  be  either  lead  or  bismuth.  The  presence  of 
either  should  be  looked  for  by  the  qualitative  test  before- 
hand. 

If  any  zinc  or  antimony  is  present  it  is  volatilised 
when  the  arsenide  of  iron  is  removed  with  borax. 


PART  III.  NICKEL  AND   COBALT  ASSAYS.  171 

The  assay  is  now  finished  according  to  instructions 
given  in  Class  B  (6)  (p.  169). 

Class  B  (d). — Some  ores  are  so  poor  in  nickel  and 
cobalt  that  they  require  a  collecting  agent,  which  can 
afterwards  be  easily  slagged  off.  Take  1^  grain  of  the 
powdered  ore ;  mix  with  0-40  grain  of  arsenide  of  iron 
(made  by  fusing  iron  filings  with  metallic  arsenic  in  a 
clay  crucible),  2  grains  potash,  3  grains  soda,  and  0'5  grain 
borax  glass ;  cover  with  a  thin  layer  of  salt,  and  finish  as 
directed  in  c  and  d,  Class  B. 

Alloys  of  copper  and  nickel  in  which  copper  pre- 
dominates cannot  be  estimated  by  the  fire  assay,  but  have 
to  be  determined  by  the  wet  way.  Alloys  of  nickel,  cobalt, 
and  antimony  cannot  be  determined  by  the  blowpipe. 

COAL. 

Coal  (or  rather  mineral  coal)  occurs  in  beds  inter- 
stratified  with  shales,  sandstones,  and  conglomerates,  and 
sometimes  limestones,  forming  distinct  layers,  which 
vary  from  a  fraction  of  an  inch  to  30  feet  or  more  in 
thickness. 

Its  hardness  varies  from  0'5  to  2*5,  and  its  specific 
gravity  from  1  to  1'80.  Lustre  dull  to  brilliant,  and  either 
earthy,  resinous,  or  submetallic.  Colour  black,  greyish 
black,  brownish  black,  and  occasionally  iridescent ;  also 
sometimes  dark  brown  and  opaque.  Fracture  conchoidal 
to  uneven. 

Brittle ;  rarely  somewhat  sectile.  Without,  taste,  ex- 
cept from  impurities  present. 

The  origin  of  coal  is  mainly  vegetable,  though  animal 
life  has  contributed  somewhat  to  the  result. 

Coal  beds  were  once  beds  of  vegetation,  which  have 
been  buried  during  different  geological  ages.  The  car- 


172      ASSAY   OF  SILVER,   GOLD,    MERCURY,   ETC.      PART  III. 

boniferous  period  furnishes  the  greatest  and  best  supply, 
but  it  is  also  found  in  beds  of  the  Triassic,  Oolitic,  Cre- 
taceous, and  Tertiary  eras. 

The  principal  varieties  of  coal  are  as  follows  : — 

Anthracite^or  Hard Coal. — Hardness  2-2-5 ;  spec.  grav. 
=  1*32— 1*70.  Contains  volatile  matter  after  drying,  3  to 
6  per  cent.  Contains  carbon,  80  to  95  per  cent.  It  has 
a  high  lustre  and  burns  without  flame,  as  it  contains 
little  or  no  bitumen.  It  is  totally  devoid  of  impressions 
of  plants,  and  is,  geologically  speaking,  the  oldest  of  all 
kinds  of  fossil  charcoal  and  is  regarded  as  the  last  stage 
of  carbonisation.  It  yields  from  1  to  7  per  cent,  of  ash, 
but  3  per  cent,  may  be  called  the  average. 

Brown  Coal,or  Lignite,  contains  from  57  to  70  per  cent. 
of  carbon,  and  represents  the  first  stage  of  carbonisation, 
and  is  a  coal  of  comparatively  recent  formation.  It  is 
composed  of  fossil  plants  more  or  less  mineralised,  and 
when  burnt  it  evolves  much  smoke  and  affords  a  dull 
flame,  and  generally  yields  a  large  quantity  of  ash.  It 
contains  from  2  to  19  per  cent,  ash  and  gives  from  30 
to  50  per  cent.  coke. 

Caking  Coal. — A  bituminous  coal  which  softens  and 
becomes  pasty  in  the  fire,  and  after  the  heat  has  been 
continued  for  a  time  the  volatile  ingredients  are  driven 
off,  and  a  greyish  black  fretted  mass  is  left.  The 
coke  obtained  from  this  coal  varies  from  50  to  85  per 
cent. 

Non-Caking  Coal  resembles  the  above  in  its  external 
character,  but  burns  freely  without  softening  or  showing 
any  appearance  of  incipient  fusion. 

Cannel  Coal.  -  A  bituminous  coal  which  generally 
cakes.  It  is  compact,  with  little  or  no  lustre,  and  has 
a  dull  black  or  greyish  black  colour.  On  distillation  it 
affords,  after  drying,  40  to  66  per  cent,  of  volatile  matter. 


PART  III.  COAL.  173 

When  held  in  the  flame  of  a  candle  it  easily  ignites, 
burning  with  a  steady  bright  flame.  It  is  used  ex- 
tensively for  the  manufacture  of  illuminating  gas,  of  which 
it  affords  a  better  quality  than  any  other  species  of  coal. 

Coal  can  be  examined  and  its  commercial  properties 
determined  by  the  blowpipe  with  great  accuracy. 

Assay. 

The  assay  is  divided  into  five  heads  : — 

1st.  The  moisture  determination. 

Select  from  the  mass  of  coal  to  be  examined  a  few 
lumps  representing  as  nearly  as  possible  the  average 
quality.  Crush  them  up  in  the  agate  mortar  into  small 
pieces  about  the  size  of  a  mustard  seed. 

Weigh  out  5  grains,  place  in  a  small  porcelain  dish, 
and  dry  at  a  gentle  heat  over  the  spirit  lamp.  Hard 
coals  sometimes  fly  when  heated,  so  it  is  best  to  cover  the 
dish  with  a  watch  glass  whilst  heating.  After  about  5 
minutes  remove  the  assay  and  weigh;  then  repeat  the 
heating  and  again  weigh.  As  soon  as  the  weights  agree 
the  assay  is  ready  to  be  converted  into  coke.  Plattner 
states  that  the  percentage  of  moisture  is  lowest  in  anthra- 
cite; in  bituminous  coals  it  is  usually  3  to  4  per  cent., 
seldom  6  to  7,  and  reaches  its  maximum  in  lignite  and 
brown  coals,  which  contain  20  per  cent,  and  sometimes 
more. 

2nd.  Determination  of  the  coke  production. 

Take  the  dried  coal  and  remove  to  a  clay  or  platinum 
crucible,  and  cover  with  a  small  roasting  clay  dish  or  plati- 
num cup.  Place  the  crucible  on  a  triangle  of  platinum  wire 
on  the  blowpipe  stand  under  the  flame,  using  alcohol,  and 
cover  it  with  a  small  sheet-iron  funnel  (the  same  that  is 
used  in  roasting  copper  ores).  The  heat  is  continued  until 
all  the  volatile  gas  has  escaped,  when  the  assay  generally 


174      ASSAY  OF  SILVER,   GOLD,   MERCURY,   ETC.     PART  III. 

will  appear  to  possess  a  fused  porous  appearance,  and  to 
have  a  metallic  lustre. 

The  coke  so  made  is  now  removed  and  weighed.  It 
should  be  weighed  quickly,  as  coke  absorbs  moisture  from 
the  air  rapidly.  The  coking  takes  about  10  minutes,  and 
the  crucible  should  not  be  allowed  to  get  beyond  a  red 
heat. 

3rd.  The  estimation  of  the  amount  of  ash. 
After  the  percentage  of  coke  has  been  determined 
remove  the  assay  to  a  small  clay  or  platinum  capsule,  and, 
without  using  a  cover,  again  heat  over  the  lamp — this  time 
to  a  bright  red  colour — until  all  the  carbon  has  been  con- 
sumed. The  operation  is  much  facilitated  by  occasionally 
stirring  the  assay  with  a  piece  of  platinum  wire,  also  by 
applying  the  blowpipe  flame  to  the  bottom  of  the  cup 
when  the  assay  is  nearly  finished. 

If  alcohol  cannot  be  obtained  the  assay  for  coke  and 
ash  can  be  conducted  in  the  charcoal  furnace  by  using 
the  blowpipe  flame,  as  in  the  copper  assay,  and  if  the  ash 
amounts  to  more  than  5  per  cent,  the  value  of  the  coal  is 
much  diminished.  If  the  ash  presents  a  brown,  red,  or 
grey  colour,  sesquioxide  of  iron  has  been  formed  by  the 
oxidation  of  the  pyrites  in  the  coal. 

4th.  Determination  of  the  absolute  heating  power  by 
Berthier's  process. 

Take  an  average  sample  of  the  coal  and  crush  it  up  to 
the  finest  powder.  Weigh  out  0'3  grain  of  the  coal  dust 
and  mix  it  with  12  grains  of  oxy chloride  of  lead,  and  after 
placing  the  mixture  in  the  crucible  cover  it  with  an  ad- 
ditional 12  grains  of  oxy  chloride  of  lead. 

Oxychloride  of  lead  fuses  more  readily  than  litharge; 
therefore,  owing  to  the  large  quantity  of  material  which 
must  be  brought  into  a  state  of  fusion  in  this  determina- 
tion, it  is  employed  instead  of  litharge. 


PART  III.  COAL.  175 

The  assay  is  next  covered  with  a  little  powdered  glass, 
also  with  a  few  spoonfuls  of  borax  glass.  A  clay  cup  is 
placed  over  the  crucible,  and  the  assay  is  then  fused  in 
the  charcoal  furnace  in  a  similar  manner  to  the  silver 
assay  when  litharge  is  used  (see  p.  122). 

About  7  or  8  minutes  suffices  to  melt  the  assay,  and  the 
lead  button  produced  by  the  carbon  in  the  coal  acting  on  the 
lead  oxychloride  will  be  found  lying  upon  the  bottom  of  the 
.crucible  when  the  assay  is  cool  and  the  crucible  is  broken. 

The  weight  of  the  button,  when  cleaned  from  the 
slag,  divided  by  20,  gives  the  quantity  of  lead  that  1 
part  of  the  fuel  under  examination  can  reduce ;  and  since 
1  part  of  carbon  reduces  34  parts  of  lead,  the  heating 
power  of  the  fuel  may  be  easily  ascertained.  The  amount 
of  lead  reduced  by  1  part  of  coal  varies  with  the  different 
pit  coals  between  21  and  32  parts,  with  the  lignites 
between  16  and  25  parts.  In  making  this  assay  the  heat 
must  be  applied  at  first  very  gradually,  and  afterwards 
increased  to  a  bright  redness. 

Dr.  Ure's  experiments,  published  in  the  '  Supplement 
to  the  Dictionary  of  Arts,  Mines,  and  Manufactures,'  have 
appeared  to  be  unsatisfactory  in  regard  to  the  accuracy  of 
Berthier's  method.  Mitchell,  however,  has  found  the 
method  correct,  and  the  author  has  found  it  equally  so. 
The  lead  oxychloride  should  always  be  pure. 

5th.  "Estimation  of  sulphur  in  a  sample  of  coal. 

Sulphur  generally  exists  in  coal  as  a  sulphide  of  iron, 
and  as  the  presence  of  more  than  2  per  cent,  of  sulphur 
depreciates  the  market  value  of  coal,  owing  to  its  destroy- 
ing the  iron  boilers  and  grates  under  and  over  which  the 
coal  is  consumed,  it  is  always  an  important  part  of  the 
examination  of  coal  to  ascertain  the  quantity  present. 

Mitchell,  in  his  '  Manual  of  Practical  Assaying,'  re- 
commends the  following  process : — 


176      ASSAY   OF  SILVER,   GOLD,   MERCURY,   ETC.      PART  III. 

'Take  1  part  of  the  finely  pulverised  coal  and  mix  with 
7  to  8  parts  of  nitre,  and  1 6  parts  of  common  salt,  and  4 
parts  of  carbonate  of  potash,  all  of  which  must  be  per- 
fectly pure.  The  mixture  is  then  placed  in  a  platinum 
crucible  and  gently  heated  at  a  certain  temperature ;  the 
whole  ignites  and  burns  quietly.  The  heat  is  then  in- 
creased until  the  mass  is  fused ;  the  operation  is  finished 
when  the  mass  is  white.  It  must,  when  cold,  be  dissolved 
in  water,  the  solution  slightly  acidulated  by  means  of 
hydrochloric  acid,  and  chloride  of  barium  added  to  it  as 
long  as  a  white  precipitate  forms.  This  precipitate  is 
sulphate  of  baryta,  which  must  be  collected  on  a  filter, 
washed,  dried,  ignited,  the  filter  burnt  away,  and  the 
remaining  sulphate  of  baryta  weighed  :  every  116  parts 
of  it  indicate  16  of  sulphur.' 

The  above-described  methods  of  examining  coal  are 
all  that  are  required  for  commercial  purposes.  The  assay 
may  be  carried  on  still  further  by  estimating  the  iron 
oxide  contained  in  the  ash,  according  to  the  instructions 
given  in  the  quantitative  iron  assay.  The  ash  can  also  be 
examined  qualitatively  for  silica,  lime,  soda,  and  potash 
(see  '  Qualitative  Determination '). 


PART   IV. 

TABLES   OF  ENGLISH  AND  AMERICAN  VALUES  OF  GOLD 

ACCORDING    TO    ITS    FINENESS; 

ALSO   THE 

VALUE   OF    GOLD   COINS   IN   THE  UNITED  STATES 
OF   AMERICA. 


PART  IV. 


ENGLISH  VALUE  OF  GOLD. 


179 


Table  of  the  English  Mint  Value  of  Gold  per  Ounce  Troy, 
at  Different  Degrees  of  Fineness. 


Fineness  of 
Gold 

Value  per  Ounce 

Fineness  of 
Gold 

Value  per  Ounce 

£   x.    d. 

£   s.    d. 

1000 

4  4  11-4545 

962 

4  1  8-7152 

999 

4  4  10-4350 

961 

4  1  7-6958 

998 

4  4  9-4156 

960 

4  1  6-6763 

997 

4  4  8-3961 

959 

4  1  5-6569 

996 

4  4  7-3767 

958 

4  1  46374 

995 

4  4  6-3572 

957 

4  1  3-6179 

994 

4  4  5-3378 

956 

4  1  2-5985 

993 

4  4  4-3183 

955 

4  1  1-5790 

992 

4  4  3-2989 

954 

4  1  05596 

991 

4  4  2-2793 

953 

4  0  11-5401 

990 

4  4  1-2600 

952 

4  0  10  5207 

989 

4  4  02405 

951 

4  0  9-5012 

988 

4  3  11-2210 

950 

4  0  8-4818 

987 

4  3  10  2016 

949 

4  0  7-4623 

986 

4  3  9-1821 

948 

4  0  6-4429 

985 

4  3  81627 

947 

4  0  5-4234 

984 

4  3  7-1432 

946 

4  0  4-4039 

983 

4  3  6-1238 

945 

4  0  3-3835 

982 

4  3  5-1043 

944 

4  0  2-3650 

981 

4  3  4-0849 

943 

4  0  13456 

980 

4  3  3-0654 

942 

4  0  03261 

979 

4  3  20459 

941 

3  19  11-3067 

978 

4  3  1-0265 

940 

3  19  10-2872 

977 

4  3  0-0070 

939 

3  19  9-2678 

976 

4  2  10  9876 

938 

3  19  8  2483 

975 

4  2  99681 

937 

3  19  7-2289 

974 

4  2  8-9487 

936 

3  19  6-2094 

973 

4  2  7-9292 

935 

3  19  5-1899 

972 

4  2  69098 

934 

3  19  4-1705 

971 

4  2  5-8903 

933 

3  19  3-1510 

970 

4  2  4-8709 

932 

3  19  2-1316 

969 

4  2  3-8504 

931 

3  19  1  1121 

968 

4  2  28319 

930 

3  19  00927 

967 

4  2  1-8125 

929 

3  18  11  0732 

966 

4  2  07930 

928 

3  18  10-0538 

965 

4  1  11-7736 

927 

3  18  9-0343 

964 

4  1  10  7541 

926 

3  18  8-0149 

963 

4  1  9-7347 

925 

3  18  6-9954 

N    2 


180   ENGLISH   AND   AMERICAN   VALUES   OF  GOLD.  PART  IV. 


Table  of  the  English  Mint  Value  of  Gold — continued. 


Fineness  of 
Gold 

Value  per  Ounce 

Fineness  of 
Gold 

Value  per  Ounce 

£  j».     d. 

£  s.     d. 

924 

3  18  5  9759 

882 

3  14  11-1589 

923 

3  18  4-9565 

881 

3  14  10-1394 

922 

3  18  3  9370 

880 

3  14  91199 

921 

3  18  2-9176 

879 

3  14  8-1005 

920 

3  18  1-8981 

878 

3  14  7-0810 

9]  9 

3  18  0-8787 

877 

3  14  6-0616 

918 

3  17  11  8592 

876 

3  14  5-0421 

917 

3  17  10-8398 

875 

3  14  4-0227 

916 

3  17  9-8203 

874 

3  14  3-0032 

915 

3  17  8-8009 

873 

3  14  1  9838 

914 

3  17  7  7814 

872 

3  14  0-9643 

913 

3  17  6-7619 

871 

3  13  11-9449 

912 

3  17  5  7425 

870 

3  13  109254 

911 

3  17  4-7230 

869 

3  13  99059 

910 

3  17  3  7036 

868 

3  13  88865 

909 

3  17  2  6841 

867 

3  13  7-8670 

9u8 

3  17  1  6647 

866 

3  13  6-8476 

907 

3  17  0-6452 

865 

3  13  5-8281 

906 

3  16  11-6258 

864 

3  13  4-8087 

905 

3  16  10-6063 

863 

3  13  37892 

904 

3  16  9-5869 

862 

3  13  2  7698 

903 

3  16  8-5674 

861 

3  13  1-7503 

902 

3  16  7-5479 

860 

3  13  0-7309 

901 

3  16  6-5285 

859 

3  12  11-7114 

900 

3  16  5-5090 

858 

3  12  10-6919 

899 

3  16  4  4896 

857 

3  12  9-6725 

898 

3  16  3-4701 

856 

3  12  8-6530 

897 

3  16  24507 

855 

3  12  7*6336 

896 

3  16  1-4312 

854 

3  12  6-6141 

895 

3  16  0-4118 

853 

3  12  5-5947 

894 

3  15  11-3923 

852 

3  12  4  5752 

893 

3  15  10  3729 

851 

3  12  3-5558 

892 

3  15  9-3534 

850 

3  12  2-5363 

891 

3  15  8-3339 

849 

3  12  1-5169 

890 

3  15  7-3145 

848 

3  12  0-4974 

889 

3  15  6  2950 

847 

3  11  11-4779 

888 

3  15  5-2756 

846 

3  11  10-4585 

887 

3  15  42561 

845 

3  11  9-4390 

886 

3  .15  3-2367 

844 

3  11  8-4196 

885 

3  15  2-2172 

843 

3  11  7-4001 

884 

3  15  1-1978 

842 

3  11  6  3807 

883 

3  15  0-1783 

841 

3  11  5-3612 

PART  IV. 


ENGLISH  VALUE   OF  GOLD. 


181 


Table  of  the  English  Mint  Value  of  Gold — continued. 


Fineness  of 
Gold 

Value  per  Ounce 

Fineness  of 
Gold 

Value  per  Ounce 

&  s.     d. 

£  s.     d. 

840 

3  11  4-3418 

798 

3  7  9-5247 

839 

3  11  3-3223 

797 

3  7  8-5052 

838 

3  11  2-3029 

796 

3  7  7-4858 

837 

3  11  1-3834 

795 

3  7  6-4663 

836 

3  11  0-2639 

794 

3  7  5-4469 

835 

3  10  11  2445 

793 

3  7  4-4274 

834 

3  10  10-2250 

792 

3  7  3-4979 

833 

3  10  9-2056 

791 

3  7  2-3885 

832 

3  10  8-1861 

790 

3  7  1-3690 

831 

3  10  7-1667 

789 

3  7  0-3496 

830 

3  10  6-1472 

788 

3  6  11-3301 

829 

3  10  5  1278 

787 

3  6  10-3107 

828 

3  10  4-1083 

786 

3  6  92912 

827 

3  10  3-0889 

785 

3  6  8-2718 

826 

3  10  2  0694 

784 

3  6  7-2523 

825 

3  10  1-0499 

783 

3  6  6-2329 

824 

3  10  0-0305 

782 

3  6  5-2134 

823 

3  9  11-0110 

781 

3  6  41939 

822 

3  9  9-9916 

780 

3  6  31745 

821 

3  9  8-9721 

779 

3  6  2-1550 

820 

3  9  7-9527 

778 

3  6  1-1356 

819 

396  9332 

777 

3  6  0-1161 

818 

3  9  5-9138 

776 

3  5  11-0967 

817 

3  9  4-8943 

775 

3  5  100772 

816 

3  9  3-8749 

774 

3  5  9-0578 

815 

3  9  2-8554 

773 

3  5  8-0383 

814 

3  9  1-8359 

772 

3  5  7-0189 

813 

3  9  0-8165 

771 

3  5  5-9994 

812 

3  8  11  7970 

770 

3  5  4-9799 

811 

3  8  10-7776 

769 

3  5  3-9605 

810 

3  8  97581 

768 

3  5  2-9410 

809 

3  8  8-7387 

767 

3  5  1-9216 

808 

3  8  7-7192 

766 

3  5  09021 

807 

3  8  66998 

765 

3  4  11-8827 

806 

3  8  5-6803 

764 

3  4  10-8632 

805 

3  8  46609 

763 

3  4  9-8438 

804 

3  8  3-6414 

762 

3  4  8-8243 

803 

3  8  2-6219 

761 

3  4  7-8049 

802 

3  8  1-6025 

760 

3  4  6-7854 

801 

3  8  0-5830 

759 

3  4  57659 

800 

3  7  11-5636 

758 

3  4  47465 

799 

3  7  10-5441 

757 

3  4  3-7270 

182  ENGLISH   AND   AMERICAN   VALUES   OF   GOLD.   PART  IV. 
Table  of  tlis  English  Mint  Value  of  Gold—  continued. 


Fineness  of 
Gold 

Value  per  Ounce 

Fineness  of 
Gold 

Value  per  Ounce 

£  5.     d. 

&   s.     d. 

756 

3  4  2-7076 

714 

3  0  7-8905 

755 

3  4  1-6881 

713 

3  0  6-8710 

754" 

3  4  0-6687 

712 

3  0  5-8516 

753 

3  3  11-6492 

711 

3  0  48321 

752 

3  3  10-6298 

710 

3  0  3-8127 

751 

3  3  96103 

709 

3  0  2-7932 

750 

3  3  8-5909 

708 

3  0  1-7738 

749 

3  3  7-5714 

707 

3  0  0-7543 

748 

3  3  6-5519 

706 

2  19  11-7349 

747 

3  3  55325 

705 

2  19  10-7154 

746 

3  3  4-5130 

704 

2  19  9-6959 

745 

3  3  3-4936 

703 

2  19  86765 

744 

3  3  24741 

702 

2  19  7-6570 

743 

3  3  1-4547 

701 

2  19  6-6376 

742 

3  3  0-4352 

700 

2  19  5-6181 

741 

3  2  11-4158 

699 

2  19  4-5987 

740 

3  2  10-3963 

698 

2  19  3-5792 

739 

3  2  9-3769 

697 

2  19  2-5598 

738 

3  2  8-3574 

696 

2  19  1-5403 

737 

3  2  7-3379 

695 

2  19  05209 

736 

3  2  6-3185 

694 

2  18  11-5014 

735 

3  2  5-2990 

693 

2  18  10-4820 

734 

3  2  42796 

692 

2  18  9-4625 

733 

3  2  3-2601       691 

2  18  84430 

732 

3  2  2-2407       690 

2  18  7-4236 

731 

3  2  1-2212 

689 

2  18  6-4041 

730 

3  2  0-2018       688 

2  18  5  3847 

729 

3  1  111823       687 

2  18  4-3652 

728 

3  1  10-1629 

686 

2  18  3-3458 

727 

3  1  91434 

685 

2  18  2-3263 

726 

3  1  8-1239 

684 

2  18  1-3069 

725 

3  1  7-1045 

683 

2  18  0-2874 

724 

3  1  6-0850 

682 

2  17  11  2680 

723 

3  1  5-0656 

681 

2  17  10  2485 

722 

3  1  4-0461 

680 

2  17  9-2290 

721 

3  1  3-0267 

679 

2  17  8-2096 

720 

312  0072 

678 

2  17  7-1901 

719 

3  1  0-9878 

677 

2  17  6-1707 

718 

3  0  11-9683 

676 

2  17  5-1512 

717 

3  0  10-9489 

675 

2  17  4-1318 

716 

3  0  9-9294 

674 

2  17  3-1123 

715 

3  0  8-9099 

673 

2  17  2-0929 

PART  IV. 


ENGLISH  VALUE  OF  GOLD. 


183 


Table  of  the  English  Mint  Value  of  Gold — continued. 


Fineness  of 
Gold 

Value  per  Ounce 

Fineness  of 
Gold 

Value  per  Ounce 

&  s.     cl. 

£  s.     d. 

672 

2  17  1-0734 

630 

2  13  6-2563 

671 

2  17  00540 

629 

2  13  5-2369 

670 

2  16  11-0345 

628 

2  13  4-2174 

669 

2  16  100151 

627 

2  13  3-1979 

668 

2  16  8-9956 

626 

2  13  2-1785 

667 

2  16  7-9761 

625 

2  13  1-1590 

666 

2  16  6  9567 

624 

2  13  0-1396 

665 

2  16  5-9372 

623 

2  12  11-1201 

664 

2  16  4-9178 

622 

2  12  10  1007 

663 

2  16  3-8983 

621 

2  12  90812 

662 

2  16  2-8789 

620 

2  12  8-0618 

661 

2  16  1-8594 

619 

2  12  7  0423 

660 

2  16  0-8399 

618 

2  12  6-0229 

659 

2  15  11-8205 

617 

2  12  5  0034 

658 

2  15  10-8010 

616 

2  12  3-9839 

657 

2  15  9-7816 

615 

2  12  2-9645 

656 

2  15  8  762] 

614 

2  12  1-9451 

655 

2  15  7-7427 

613 

2  12  0  9256 

654 

2  15  6-7232 

612 

2  11  11-9061 

653 

2  15  5-7038 

611 

2  11  10-8867 

652 

2  15  4-6843 

610 

2  11  9-8672 

651 

2  15  3  6649 

609 

2  11  8-8478 

650 

2  15  2-6454 

608 

2  11  7-8283 

649 

2  15  1-6259 

607 

2  11  6  8089 

648 

2  15  0  6065 

606 

2  11  5-7894 

647 

2  14  11  5870 

605 

2  11  4-7699 

646 

2  14  10-5676 

604 

2  11  3  7505 

645 

2  14  9-5481 

603 

2  11  2-7311 

644 

2  14  8-5287 

602 

2  11  1-7116 

643 

2  14  7-5092 

601 

2  11  0-6921 

642 

2  14  6-4898 

600 

2  10  11-6727 

641 

2  14  5-4703 

599 

2  10  10-6532 

640 

2  14  4-4509 

598 

2  10  9-6338 

639 

2  14  3-4314 

597 

2  10  8-6143 

638 

2  14  2-4120 

596 

2  10  7-5949 

637 

2  14  1-3925 

595 

2  10  6-5754 

636 

2  14  0-3730 

594 

2  10  5  5559 

635 

2  13  11-3536 

593 

2  10  4-5365 

634 

2  13  10-3341 

592 

2  10  3-5170 

633 

2  13  9-3147 

591 

2  10  2-4976 

632 

2  13  8-2952 

590 

2  10  1-4781 

631 

2  13  7-2758 

589 

2  10  0-4587 

184   ENGLISH  AND  AMEEICAN  VALUES  OF   GOLD.   PART  IV. 


Table  of  the  English  Mint  Value  of  Gold — continued. 


Fineness  of 
Gold 

Value  per  Otmce 

Fineness  of 
Gold 

Value  per  Ounce 

£   .?.    (1. 

£   s.    d. 

588 

2  9  114392 

546 

2  6  4-6221 

587 

2  9  10-4198 

545 

2  6  36027 

586 

2  9  9-4003 

544 

2  6  2-5832 

585 

2  9  8-3809 

543 

2  6  1-5638 

584 

2  9  73614 

542 

2  6  05443 

583 

2  9  6-3419 

541 

2  5  11-5249 

582 

2  9  5-3225 

540 

2  5  10  5054 

581 

2  9  4-3030 

539 

2  5  9-4859 

580 

2  9  3-2836 

538 

2  5  8-4665 

579 

2  9  2-2641 

537 

2  5  7-4470 

578 

2  9  12447 

536 

2  5  6-4276 

577 

2  9  0-2252 

535 

2  5  5-4081 

576 

2  8  11-2058 

534 

2  5  4-3887 

575 

2  8  10-1863 

533 

2  5  33692 

574 

2  8  9-1669 

532 

2  5  2-3498 

573 

2  8  8-1474 

531 

2  5  13303 

572 

2  8  7-1279 

530 

2  5  0-3109 

571 

2  8  6-1085 

529 

2  4  11-2914 

570 

2  8  5-0890 

528 

2  4  10-2719 

569 

2  8  4-0696 

527 

2  4  9-2525 

568 

2  8  3-0501 

526 

2  4  8-2330 

567 

2  8  2-0307 

525 

2  4  7-2136 

566 

2  8  1-0112 

524 

2  4  6-1941 

565 

2  7  11-9918 

523 

2  4  5-1747 

564 

2  7  109723 

522 

2  4  4-1552 

563 

2  7  9-9529 

521 

2  4  3-1358 

562 

2  7  8-9334 

520 

2  4  21163 

561 

2  7  7-9140 

519 

2  4  1-0969 

560 

276  8945 

518 

2  4  0-0774 

559 

2  7  5-8751 

517 

2  3  11-0579 

558 

2  7  4-8556 

516 

2  3  10-0385 

557 

2  7  3-8361 

515 

2  3  9-0190 

556 

2  7  2-8167 

514 

2  3  7-9996 

555 

2  7  1-7972 

513 

2  3  6-9801 

554 

2  7  0-7778 

512 

2  3  5-9607 

553 

2  6  11-7583 

511 

2  3  4-9412 

552 

2  6  10-7389 

510 

2  3  3-9218 

551 

2  6  97194 

509 

2  3  2-9023 

550 

2  6  8-6999 

508 

2  3  1-8829 

549 

2  6  7-6805 

507 

2  3  0-8634 

548 

2  6  6-6611 

506 

2  2  11-8439 

547 

2  6  5-6416 

505 

2  2  10-8245 

i 

FART  IV. 


ENGLISH  VALUE  OF  GOLD. 


185 


Table  of  tlie  English  Mint  Value  of  Gold— continued. 


Fineness  of 
Gold 

Value  per  Ounce 

Fineness  of 
Gold 

Value  per  Ounce 

£   .?.    d. 

£  s.     d. 

504 

2  2  9-8051 

462 

1  19  2-9879 

503 

2  2  8-7856 

461 

1  19  1-9685 

502 

2  2  77661 

460 

1  19  0-9490 

501 

2  2  6-7467 

459 

1  18  11-9296 

500 

2  2  5-7272 

458 

1  18  10-9101 

499 

2  2  4-7078 

457 

1  18  9-8907 

498 

2  2  3-6883 

456 

1  18  8-8712 

497 

2  2  2-6689 

455 

1  18  7-8518 

496 

2  2  1-6494 

454 

1  18  6-8323 

495 

2  2  0-6300 

453 

1  18  5-8129 

494 

2  1  11-6105 

452 

1  18  4-7934 

493 

2  1  10-5911 

451 

1  18  3-7739 

492 

2  1  9-5716 

450 

1  18  2-7545 

491 

2  1  8-5521 

449 

1  18  1-7351 

490 

2  1  7-5327 

448 

1  18  0-7156 

489 

2  1  1-5132 

447 

1  17  11-6961 

488 

2  1  5-4938 

446 

1  17  10-6767 

487 

2  1  4-4743 

445 

1  17  9-6572 

486 

2  1  3-4549 

444 

1  17  8-6378 

485 

2  1  2-4354 

443 

1  17  7-6183 

484 

2  1  1-4159 

442 

1  17  6-5989 

483 

2  1  0-3965 

441 

1  17  5-5794 

482  . 

2  0  11-3770 

440 

1  17  4-5599 

481 

2  0  10-3576 

439 

1  17  3-5405 

480 

2  0  9-3381 

438 

1  17  2-5211 

479 

2  0  8-3187 

437 

1  17  1-5016 

478 

2  0  7-2992 

436 

1  17  0-4821 

477 

2  0  6-2798 

435 

1  16  11-4627 

476 

2  0  5-2603 

434 

1  16  10-4432 

475 

2  0  4-2409 

433 

1  16  9-4238 

474 

2  0  3-2214 

432 

1  16  8-4043 

473 

2  0  2-2020 

431 

1  16  7-3849 

472 

2  0  1-1825 

430 

1  16  6-3654 

471 

2  0  0-1630 

429 

1  16  5-3459 

470 

1  19  11-1436 

428 

1  16  4-3265 

469 

1  19  10-1241 

427 

1  16  3-3070 

468 

1  19  9-1047 

426 

1  16  2-2876 

467 

1  19  8-0852 

425 

1  16  1-2681 

466 

1  19  7-0658 

424 

1  16  0-2487 

465 

1  19  6-0463 

423 

1  15  11-2292 

464 

1  19  5-0269 

422 

1  15  10-2098 

463 

1  19  4-0074 

421 

1  15  9-1903 

186  ENGLISH   AND  AMERICAN  VALUES   OF   GOLD.   PART  IV. 


Table  of  tlw  English  Mint  Value  of  Gold — continued. 


Fineness  of 
Gold 

Value  per  Ounce 

Fineness  of 
Gold 

Value  per  Ounce 

£  *.     d. 

£  .?.     d. 

420 

1  15  8-1709 

378 

1  12  1-3538 

419 

1  15  7-1514 

377 

1  12  0-3343 

418 

1  15  6-1319 

376 

1  11  11-3142 

417 

1  15  5-1125 

375 

1  11  10-2954 

416 

1  15  4-0930 

374 

1  11  9-2759 

415 

1  15  3-0736 

373 

1  11  8-2565 

414 

1  15  2-0541 

372 

1  11  7-2370 

413 

1  15  1-0347 

371 

1  11  6-2176 

412 

1  15  0-0152 

370 

1  11  5-1981 

411 

1  14  10-9958 

369 

1  11  4-1787 

410 

1  14  9-9763 

368 

1  11  3-1592 

409 

1  14  8-9569 

367 

1  11  2-1398 

408 

1  14  7-9374 

366 

1  11  1-1203 

407 

1  14  6-9179 

365 

1  11  0-1009 

406 

1  14  5-8985 

364 

1  10  11-0814 

405 

1  14  4-8790 

363 

1  10  10-0620 

404 

1  14  3-8596 

362 

1  10  9-0425 

403 

1  14  2-8401 

361 

1  10  8-0230 

402 

1  14  1-8207 

360 

1  10  7-0036 

401 

1  14  0-8012 

359 

1  10  5-9841 

400 

1  13  11-7818 

358 

1  10  4-9647 

399 

1  13  10-7623 

357 

1  10  3-9452 

398 

1  13  9-7429 

356 

1  10  2-9258 

397 

1  13  8-7234 

355 

1  10  1-9063 

396 

1  13  7-7039 

354 

1  10  0-8869 

395 

1  13  6-6845 

353 

1  9  11-8674 

394 

1  13  5-6651 

352 

1  9  10-8479 

393 

1  13  4-6456 

351 

1  9  9-8285 

392 

1  13  3-6261 

350 

1  9  8-8090 

391 

1  13  2-6067 

349 

1  9  7-7896 

390 

1  13  1-5872 

348 

1  9  6-7701 

389 

1  13  0-5678 

347 

1  9  5-7507 

388 

1  12  11-5483 

346 

1  9  4-7312 

387 

1  12  10-5289 

345 

1  9  3-7118 

386 

1  12  9-5094 

344 

1  9  2-6923 

385 

1  12  8-4899 

343 

1  9  1-6729 

384 

1  12  7-4705 

342 

1  9  0-6534 

383 

1  12  6-4511 

341 

1  8  11-6339 

382 

1  12  5-4316 

340 

1  8  10-6145 

381 

1  12  4-4121 

339 

1  8  9-5951 

380 

1  12  3-3927 

338 

1  8  8-5756 

379 

1  12  2-3732 

3S7 

1  8  7-5561 

PART  IV. 


ENGLISH  VALUE   OF  GOLD. 


187 


Table  of  the  English  Mint  Value  of  Gold— continued. 


Fine-ness  of 
Gold 

Value  per  Ounce 

Fineness  of 
Gold 

Value  per  Ounce 

&   s.    d. 

£   s.     d. 

336 

1  8  6-5367 

294 

1  4  11-7196 

335 

1  8  5-5172 

293 

1  4  10-7011 

334 

1  8  4-4978 

292 

1  4  9-6807 

333 

1  8  3-4783 

291 

1  4  8-6612 

332 

1  8  2-4589 

290 

1  4  7-6418 

331 

1  8  1-4394 

289 

1  4  6-6223 

330 

1  8  0-4199 

288 

1  4  5-6029 

329 

1  7  11  4005 

287 

1  4  4-5834 

328 

1  7  10-3811 

286 

1  4  3-5639 

327 

1  7  9-3616 

285 

1  4  2-5445 

326 

1  7  83421 

284 

1  4  1-5251 

325 

1  7  7-3227 

283 

1  4  0-5056 

324 

1  7  6-3032 

282 

1  3  11-4861 

323 

1  7  5-2838 

281 

1  3  10-4667 

322 

1  7  4-2643 

280 

1  3  9-4472 

321 

1  7  32449 

279 

1  3  8-4278 

320 

1  7  22254 

278 

1  3  7-4083 

319 

1  7  1-2059 

277 

1  3  6-3889 

318 

1  7  0-1865 

276 

1  3  5-3694 

317 

1  6  11-1670 

275 

1  3  4-3499 

316 

1  6  10-1476 

274 

1  3  3-3305 

315 

1  6  9-1281 

273 

1  3  2-3110 

314 

1  6  8-1087 

272 

1  3  1-2916 

313 

1  6  7-0892 

271  " 

1  3  0-2721 

312 

1  6  6-0698 

270 

1  2  11-2527 

311 

1  6  5-0503 

269 

1  2  10-2332 

310 

1  6  4-0309 

268 

1  2  9-2138 

309 

1  6  3-0114 

267 

1  2  8-1943 

308 

1  6  1-9919 

266 

1  2  7-1749 

307 

1  6  0-9725 

265 

1  2  6-1554 

306 

1  5  11-9530 

264 

1  2  5-1351 

305 

1  5  10-9336 

263 

1  2  4-1165 

304 

1  5  9-9141 

262 

1  2  3-0970 

303 

1  5  8-8947 

261 

1  2  2-0776 

302 

1  5  7-8752 

260 

1  2  1-0581 

301 

1  5  6-8558 

259 

1  2  0-0387 

300 

1  5  5-8363 

258 

1  1  11-0192 

299 

1  5  4-8169 

257 

1  1  9-9998 

298 

1  5  3-7974 

256 

1  1  8-9803 

297 

1  5  2-7779 

255 

1  1  7-9609 

296 

1  5  1-7585 

254 

1  1  6-9414 

295 

1  5  0-7390 

253 

1  1  5-9219 

188   ENGLISH  AND   AMERICAN   VALUES   OF   GOLD.  PART  IV 


Table  of  the  English  Mint  Value  of  Gold— continued. 


Fineness  of 
Gold 

Value  per  Ounce 

Fineness  of 
Gold 

Value  per  Ounce 

£   *.     d. 

£  s.     (I. 

252 

1  1  4-9025 

210 

0  17  10-0854 

251 

1  1  3-8830 

209 

0  17  9-0659 

250 

1  1  2-8636 

208 

0  17  8-0465 

249 

1  1  1-8441 

207 

0  17  7-0270 

248 

1  1  0-8247 

206 

0  17  6-0076 

247 

1  0  11-8052 

205 

0  17  4-9881 

246 

1  0  10-7858 

204 

0  17  3-9687 

245 

1  0  9-7663 

203 

0  17  2-9492 

244 

1  0  8-7469 

202 

0  17  1-9298 

243 

1  0  7-7274 

201 

0  17  0-9103 

242 

1  0  6-7079 

200 

0  16  11-8909 

241 

1  0  5-6885 

199 

0  16  10-8714 

240 

1  0  4-6690 

198 

0  16  9-8519 

239 

1  0  3-6496 

197 

0  16  8-8325 

238 

1  0  2-6301 

196 

0  16  7-8130 

237 

1  0  1-6107 

195 

0  16  6-7936 

236 

1  0  0-5912 

194 

0  16  5-7741 

235 

0  19  11-5718 

193 

0  16  4-7547 

234 

0  19  10-5523 

192  , 

0  16  3-7352 

233 

0  19  9-5329 

191 

0  16  2-7158 

232 

0  19  8-5134 

190 

0  16  1-6963 

231 

0  19  7-4939 

189 

0  16  0-6769 

230 

0  19  6-4745 

188 

0  15  11-6574 

229 

0  19  5-4551 

187 

0  15  10-6379 

228 

0  19  4-4356 

186 

0  15  9-6185 

227 

0  19  3-4161 

185 

0  15  8-5990 

226 

0  19  2-3967 

184 

0  15  7-5796 

225 

0  19  1-3772 

183 

0  15  6-5601 

224 

0  19  0-3578 

182 

0  15  5-5407 

223 

0  18  11-3383 

181 

0  15  4-5212 

222 

0  18  10-3189 

180 

0  15  3-5018 

221 

0  18  9-2994 

179 

0  15  2-4823 

220 

0  18  8-2799 

178 

0  15  1-4629 

219 

0  18  7-2605 

177 

0  15  0-4434 

218 

0  18  6-2410 

176 

0  14  11-4239 

217 

0  18  5-2216 

175 

0  14  10-4045 

216 

0  18  4-2021 

174 

0  14  9-3851 

215 

0  18  3-1827 

173 

0  14  8-3656 

214 

0  18  2-1632 

172 

0  14  7-3461 

213 

0  18  1-1438 

171 

0  14  6-3267 

212 

0  18  0-1243 

170 

0  14  5-3072 

211 

0  17  11-1049 

169 

0  14  4-2878 

PART  IV. 


ENGLISH  VALUE  OF   GOLD. 


189 


Table  uf  the  English  Mint  Value  of  Gold — continued. 


Fineness  of 
ttold 

Value  per  Ounce 

Fineness  of 
Gold 

Value  per  Ounce 

£  s.     d. 

£  x.     d. 

168 

0  14  3-2683 

126 

0  10  8-4512 

167 

0  14  2-2489 

125 

0  10  7-4318 

166 

0  14  1-2294 

124 

0  10  6-4123 

165 

0  14  0-2099 

123 

0  10  5-3929 

164 

0  13  11-1905 

122 

0  10  4-3734 

163 

0  13  10-1710 

121 

0  10  3-3530 

162 

0  13  9-1516 

120 

0  10  2-3345 

161 

0  13  8-1321 

119 

0  10  1-3151 

160 

0  13  7-1127 

118 

0  10  0-2956 

159      0  13  6-0932 

117 

0  9  11-2761 

158      0  13  5-0738 

116 

0  9  10-2567 

157 

0  13  4-0543 

115 

0  9  9-2372 

156 

0  13  3-0349 

114 

0  9  8-2178 

155 

0  13  2-0154 

113 

0  9  7-1983 

154 

0  13  0-9959 

112 

0  9  6-1789 

153 

0  12  11-9765 

111 

0  9  5-1594 

152 

0  12  10-9570 

110 

0  9  4-1399 

151 

0  12  9-9376 

109 

0  9  3-1205 

150 

0  12  8-9181 

108 

0  9  2-1010 

149 

0  12  7-8987 

107 

0  9  1-0816 

148 

0  12  6-8792 

106 

0  9  0-0621 

147 

0  12  5-8598 

105 

0  8  11-0427 

146 

0  12  4-8403 

104 

0  8  10-0232 

145 

0  12  3-8209 

103 

0  8  9-0038 

144.      0  12  2-8014 

102 

0  8  7-9843 

143 

0  12  1-7819 

101 

0  8  6-9649 

142 

0  12  0-7625 

100 

0  8  5-9454 

141 

0  11  11-7430 

99 

0  8  4-9259 

140 

0  11  10-7236 

98 

0  8  3-9065 

139 

0  11  9-7041 

97 

0  8  2-8870 

138 

0  11  8-6847 

96 

0  8  1-8676 

137 

0  11  7-6652 

95 

0  8  0-8481 

136 

0  11  6-6458 

94 

0  7  11-8287 

135 

0  11  5-6263 

93 

0  7  10-8092 

134 

0  11  4-6069 

92 

0  7  9-7898 

133 

0  11  3-5874 

91 

0  7  8-7703 

132 

0  11  2-5679 

90 

0  7  7-7509 

131 

0  11  1-5485 

89 

0  7  6-7314 

130 

0  11  0-5290 

88 

0  7  5-7119 

129 

0  10  11-5096 

87 

0  7  4-6925 

128 

0  10  10-4901 

86 

0  7  3-6730 

127 

0  10  9-4707 

85 

0  7  2-6536 

190   ENGLISH  AND  AMERICAN   VALUES   OF  GOLD.   PART  IV. 


Table  of  the  English  Mint  Value  of  Gold — continued. 


Fineness  of 
Gold 

Value  per  Ounce 

Fineo  ess  of 
Gold 

Value  per  Ounce 

&  s.     d. 

£  s.     d. 

84 

0  7  1-6341 

42 

0  3  6-8170 

83 

0  7  0-6147 

41 

0  3  5-7976 

82 

0  6  11-5952 

40 

0  3  4-7781 

81 

0  6  10  5758 

39 

0  3  3-7587 

80 

0  6  9-5563 

38 

0  3  2-7392 

79 

0  6  8-5369 

37 

0  3  1-7198 

78 

0  6  7-5174 

36 

0  3  0-7003 

77 

0  6  6-4979 

35 

0  2  11-6809 

76 

0  6  5-4785 

34 

0  2  106614 

75 

0  6  4-4590 

33 

0  2  9-6419 

74 

0  6  3-4396 

32 

0  2  8-6225 

73 

0  6  24201 

31 

0  2  7-6030 

72 

0  6  1-4007 

30 

0  2  6-5836 

71 

0  6  0-3812 

29 

0  2  5-5641 

70 

0  5  11-3618 

28 

0  2  45447 

69 

0  5  10-3423 

27 

0  2  3-5252 

68 

0  5  9-3229 

26 

0  2  2-5058 

67 

0  5  8-3034 

25 

0  2  1-4863 

66 

0  5  7-2839 

24 

0  2  0-4669 

65 

0  5  6-2645 

23 

0  1  11  4474 

64 

0  5  5-2451 

22 

0  1  10-4279 

63 

0  5  4-2256 

21 

0  1  9-4085 

62 

0  5  3-2061 

20 

0  1  8-3890 

61 

0  5  2-1867 

19 

0  1  7-3696 

60 

0  5  1-1672 

18 

0  1  6-3501 

59 

0  5  01478 

17 

0  1  5-3307 

58 

0  4  11-1283 

16 

0  1  4-3112 

57 

0  4  10-1089 

15 

0  1  3-2918 

56 

0  4  9-0894 

14 

0  1  2-2723 

55 

0  4  8-0699 

13 

0  1  1-2529 

54 

0  4  7-0505 

12 

0  1  0-2334 

53 

0  4  6-0310 

11 

0  0  11-2139 

52 

0  4  5-0116 

10 

0  0  10  1945 

51 

0  4  3-9921 

9 

0  0  9-1750 

50 

0  4  2-9727 

8 

0  0  8-1556 

49 

0  4  1-9532 

7 

0  0  7-1361 

48 

0  4  09338 

6 

0  0  6-1167 

47 

0  3  11-9143 

5 

0  0  5-0972 

46 

0  3  10-8949 

4 

0  0  4-0778 

45 

0  3  9-8754 

3 

0  0  3-0583 

44 

0  3  8-8559 

2 

0  0  2-0389 

43 

0  3  7-8365 

1 

0  0  1-0194 

PART  IV.       GOLD   COINS  IN  THE  U.S.   OF  AMERICA. 


191 


GOLD  COINS  IN  THE  UNITED  STATES  OP 
AMERICA. 

The  following  table  of  gold  coins  is  taken  from  the 
annual  report  of  the  Director  of  the  United  States  Mint. 

From  the  value  of  the  gold  coins  a  deduction  of  a 
half  of  one  per  cent,  is  made  to  cover  the  cost  of  recoin- 
age. 

The  weights  of  coins  are  usually  expressed  in  grains, 
but  in  this  table  they  have  been  reduced  to  troy  ounces 
and  decimals ;  but  these  weights  are  readily  converted 
into  grains  again  by  multiplying  them  by  480,  or  grains 
into  ounces  and  decimals  by  dividing  them  by  480. 

U.S.A.  gold  eagle,  weighing  258  grs.  or  0*5375  oz.,  is 
worth  $10-00. 

Table  of  the  Value  of  Gold  Coins  in  the  United  States  of  America. 


Country 

Denominations 

Weight 

Fine- 
ness 

Value 

Value 
after  De- 
duction 

I 

Oz.  Dec. 

lOOOths 

$ 

$ 

Australia  . 

Pound  of  ]  852 

0-281 

916-5 

5-32-37 

5-29-71 

Australia  . 

Sovereign  of  '55-60 

0-256-5 

916 

4-85-58 

4-83-16 

Austria 

Ducat    . 

0-112 

986 

2-28-28 

2-27-04 

Austria 

Souverain 

0-363 

900 

6-75-35 

6-71-98 

Austria 

New  Union  Crown 

(assumed) 

0-357 

900 

6-64-19 

6-60-87 

Belgium    . 

Twenty-five  francs 

0-254 

899 

4-72-03 

4-69-67 

Bolivia 

Doubloon 

0-867 

870 

15-59-25 

15-51-46 

Brazil 

Twenty  milreis 

0-575 

917-5 

10-90-57 

10-85-12 

Central  America 

Two  escudos  . 

0-209 

853-5 

3-68-75 

3-66-91 

Central  America 

Four  reals 

0-027 

875 

0-48-8 

0-48-6 

Chili 

Old  doubloon 

0-867 

870 

15-59-26 

15-51-47 

Chili 

Ten  pesos  '  condor  ' 

0-492 

900 

9-15-35 

9-10-78 

Denmark  . 

Ten  thaler     . 

0-427 

895 

7-90-01 

7-86-06 

Ecuador     . 

Four  escudos 

0-433 

844 

7-55-46 

7-51-69 

England    . 

Pound  or  sovereign, 

new  . 

0-256-7 

916-5 

4-86-34 

4-83-91 

England    . 

Pound  or  sovereign, 

average 

0-256-2 

916 

4-84-92 

4-82-50 

France 

Twenty  f  rancs,new 

0-207-5 

899-5 

3-85-83 

3-83-91 

France 

Twenty  francs,  av. 

0-207 

899 

3-84-69 

3-82-77 

192    ENGLISH   AND   AMEEICAN   VALUES   OF   GOLD.    PART  IV. 


Table  of  the  Value  of  Gold  Coins — continued. 


Country 

Denominations 

Weight 

Fine- 
ness 

Value 

Value 
after  De- 
duction 

Oz.  Dec. 

lOOOths 

$ 

• 

Germany,  North 

Ten  thaler     . 

0-427 

895 

7-90-01 

7-86  06 

Germany,  North 

Ten  thaler,  Prussian 

0-427 

903 

7-97-07 

7-93-OD 

Germany,  North 

Krone  (crown) 

0-357 

900 

6-64-20 

6-60-88 

Germany,  South 

Ducat    . 

0-112 

986 

2-28-28 

227-14 

Greece 

Twenty  drachms  . 

0-185 

900 

3  44-19 

3-42-47 

Hindostan 

Mohur  . 

0-874 

916 

7-08-18 

7-04-64 

Italy 

Twenty  lire  . 

0-207 

898 

3-84-26 

382-34 

Japrtn 

Old  cobang  . 

0362 

568 

4-44-0 

4-41-8 

Japan 

New  cobang  . 

0-289 

572 

3-57-6 

3-55-8 

Mexico 

Doubloon,  average 

0-867-5 

866 

15-52-98 

15-45-22 

Mexico 

Doubloon,  new 

0-867-5 

870-5 

15-61-05 

15-53-25 

Naples 

Six  ducati,  new 

0-245 

996 

5-04-43 

5-01-91 

Netherlands 

Ten  guilders  . 

0-215 

899 

3-99-56 

3-97-57 

New  Granada   . 

Old  doubloon 

(Bogota)  . 

0-868 

870 

15-61-06 

15-53-26 

New  Granada    . 

Old  doubloon 

(Popayan) 

0-867 

858 

15-37-75 

15-30-07 

New  Granada    . 

Ten  pesos,  new 

0-525 

891-5 

9-67-51 

9-62-68 

Peru  . 

Old  doubloon 

0-867 

868 

15-55-67 

1547-90 

Peru  . 

Twenty  soles  (solde 

• 

oro)  . 

1-035 

898 

19-21-8 

19-12-2 

Portugal    . 

Gold  crown   . 

0-308 

912 

5-80-66 

5"77"76 

Prussia 

New  Union  crown 

(assumed)          .* 

0-357 

900 

6-64-19 

6-60-87 

Rome 

2^  scudi,  new 

0-140 

900 

2-60-47 

2-59-17 

Russia 

Five  roubles  . 

0-210 

916 

3-97-64 

3-95-66 

Spain 

100  reals 

0-268 

896 

4-96-39 

4-93-91 

Spain 

80  reals 

0-215 

869-5 

3-86-44 

3-84-51 

Sweden 

Ducat    . 

0-111 

975 

2-23-72 

2-22-611 

Tunis 

25  piastres     . 

0-161 

900 

2-99-54 

2-98-05 

Turkey 

100  piastres  . 

0-231 

915 

4-3693 

434-75 

Tuscany     . 

Sequin  . 

0-112 

999 

2-31-29 

2-30-14 

Explanation  of  Gold  Table. 

The  values  per  oz.  of  gold  in  the  following  tables  are 
computed  from  the  simple  formula  that  387  oz.  of  pure 
gold  (1,000  fine)  are  worth  $8,000.  Hence  1  oz.  is  worth 
$20-671834625  and  the  r^-of  an  oz.  (decimally  expressed 
as  -001  fine)  is  worth  $0-020671834625. 

What  we  usually  call  fineness,  therefore,  is  simply  the 


PART  IV.       GOLD   COINS  IN  THE  U.S.   OF  AMERICA.          193 

•weight  of  fine  metal  contained  in  any  given  quantity  of 
mixed  metals  or  alloys.  For  instance,  in  a  gold  or  silver 
bar  which  is  reported  to  be  850  fine,  it  is  simply  meant 
that  in  1,000  parts  by  weight  850  are  fine  gold  or  fine 
silver,  as  the  case  may  be. 

In  our  mints  the  value  of  gold  is  computed  from 
standard  weight — that  is,  gold  which  is  900  fine,  that 
being  the  fineness  of  our  gold  coin  as  required  by  law. 
The  formula  in  this  case  is,  43  oz.  of  standard  gold  are 
worth  $800.  Hence  multiply  standard  ozs.  by  800  and 
divide  by  43,  and  you  obtain  the  value. 

Example.— Take  123TW  oz.  at  843  fine,  and  we  ob- 
tain the  result  thus :  — 

123*13  oz.  gross  weight. 
843  fineness  of  gold. 

36939 
49252 
98504 


U.S.  standard  900  )  103J98-59  oz.  of  fine  gold. 


115331 
800 

43  )  92264-800 


#2145-69    value. 

To  find  value  per  oz.,  divide  total  value  (2145-69)  by 
standard  ozs.  (115-331),  and  you  have  $18-60.46,  which 
will  be  seen,  by  reference  to  the  table,  is  the  value  of  1  oz. 
of  gold  at  900  fine. 

The  value  in  this  case  would  have  been  ascertained 

o 


194   ENGLISH  AND   AMERICAN  VALUES   OF   GOLD.   PART  IV. 

thus : — By  reference  to  the  gold  table  and  opposite  '843 
the  value  of  1  oz.  -843  fine  is  #17-4264.     Hence 

123-13 
174264 


492-52 
73878 
24626 
49252 
86191 
12313 

£2145-69    value. 


PART  IV.   VALUE  OF   GOLD   IN  THE  U.S.    OF  AMERICA.    195 


Table  of  the  Value  of  Gold  per  Ounce  Troy,  at  Different  Degrees 
of  Fineness,  in  the  United  States  of  America. 


B 

£ 

^H                         CO 

1   1 

£3 

1     5 

3          ^ 

1  I    I 

a) 

I  s 

8 
E 

1      <§ 

0 

0  00-00 

10 

0  20-67 

20 

0  41-34 

30 

0  62-02 

40 

0  82-69 

i 

0  01-03 

0  21-71 

0  42-38 

0  63-05 

0  83-72 

i 

0  02-07 

II2 

0  22-74 

21 

0  43-41 

31 

0  64-08 

41 

0  84-75 

i 

0  03-10 

4- 

0  23-77 

1 

0  44-44: 

| 

0  65-12 

£ 

0  85-79 

2 

0  04-13 

12 

0  24-81 

22 

0  45-48 

32 

0  66-15 

42 

0  86-S2 

1 

0  05-17 

i 

0  25-84 

i 

0  46-51 

i 

0  67-18 

A 

0  87-86 

32 

0  06-20 

13 

0  26-87 

23 

0  47-55;  33" 

0  68-22 

43' 

0  88-89 

I       2 

0  07-24 

£ 

0  27-91 

1 

0  48-581 

i 

0  69-25 

1 

0  89-92 

4 

0  08-27 

14 

0  28-94 

24 

0  49-61: 

34 

0  7028 

44 

0  90-96 

i 

0  09-30 

l 

0  29-97 

i 

0  50-65 

_L 

0  71-32 

i 

0  91-99 

5 

0  10-34 

15 

0  31-01 

25  2 

0  51-68 

352 

0  72-35 

45 

0  93-02 

1 

0  11-37 

i 

0  32-04 

l 

0  52-71 

i 

0  73-39 

JL 

0  94-06 

6 

0  12-40 

16 

0  33-07 

26' 

0  53-75 

36 

0  74-42 

46 

0  95-09 

i 

0  13-44 

1 

0  34-11 

1 

0  54-78 

± 

0  75-45 

l 

0  96-12 

7' 

0  14-47 

17" 

0  35-14 

27' 

0  55-81 

37 

0  76-49 

47 

0  97-16 

i   i 

0  15-50 

1 

0  36-18 

l 

0  56-85 

i. 

0  77-52 

^ 

0  98-19 

8 

0  16-54 

is' 

0  37-21 

28 

0  57-88 

38 

0  78-55 

48 

0  99-22 

£ 

0  17-57 

| 

0  38-24 

| 

0  58-91 

i 

0  79-59 

i 

1  00-26 

9 

0  18-60 

19 

0  39-28 

29 

0  59-95 

39' 

0  80-62 

49 

1  01-29 

* 

0  19-64 

2 

0  40-31 

* 

0  60-98 

* 

0  81-65 

*] 

1  02  '33 

| 

1     -s 

H 

8 

£ 

1      1 
Q        ° 

1 

E 

2                CO 

•5       "S 

1          0 

1 

1      I 

5      d 

o> 
e 

S 

I     1 

50 

1  03-36 

60 

1  24-03 

70 

1  44-70 

80 

1   65-37 

90 

1  86-05 

i 

1  04-39 

i 

1  25-06 

i 

1  45-74 

J 

1  66-41 

^ 

1  87-08 

51 

1  05-43 

61 

1  26-10 

71 

1  46-77 

81 

1  67-44 

91 

1  88-11 

i 

1  06-46 

i 

1  27-13 

i 

1  47-80 

1 

1  68-48 

1 

1  89-15 

52' 

1  07-49 

62' 

1  28-17 

72' 

1  48-84 

82' 

1  69-51 

92 

1  90-18 

i 

1  08-53 

i. 

1  29-20 

i 

1  49-87 

i 

1  70-54 

i 

1  91-21 

53' 

1  09-56 

;63 

1  30-23 

73 

1  50-90 

83  2 

1  71-58 

93 

1  92-25 

1 

1  10-59 

^ 

1  31-27 

i 

1  51-94, 

l 

1  72-61 

i 

1  93-28 

54' 

1  11-63 

64 

1  32-30 

74 

1  52-97 

84' 

1  73-64 

94 

1  94-32 

i 

1  12-66 

i 

1  33-33 

i 

54-01 

i 

1  74-68 

i 

1  95-35 

55 

1   13-70 

65 

1  34-37 

75 

55-04 

85' 

1  75-71 

95' 

1  96-38 

l 

1  14-73 

i 

1  35-40 

i 

56-07 

i 

1  76-74 

i 

1  97-42 

562 

1  15-76 

66 

1   36-43 

76 

57-11  i 

862 

1  77-78 

96' 

1  98-45 

1 

1  16-80 

i 

1  37-47 

1 

58-14) 

i 

1  78-81 

| 

1  99-48 

57 

1  17-83 

67 

1  38-50 

77 

59-171 

87 

1  79-84 

97 

2  00-52 

£ 

1  18-86 

i 

1  39-53 

i 

60-21 

i 

1  80-88 

^ 

2  01-55 

68 

1  19-90 

68 

1  40-57  ! 

78 

61-24 

88" 

1  81-91 

98 

2  02-58 

i 

1  20-93 

± 

1  41-60 

l 

62-27 

i 

1  82-95 

£ 

2  03-62 

59 

1  21-96 

69 

1  42-641 

79 

1  63-31 

89' 

1  83-98 

99' 

2  04-65 

* 

1  23-00 

* 

1  43-67  | 

2 

1  64-34 

* 

1  85-01 

2 

2  05-68 

o  2 


196    ENGLISH  AND   AMERICAN  VALUES   OF   GOLD,   PART  IV. 


Table  of  the  Value  of  Gold — continued. 


0) 

|      42 

' 

p       2 

2 

i     " 

o 

2        w 

o 

1     a 

1 

1 

a      s 
1     <3 

£ 

1 

£ 

1    B 

E 

1  i 

100 

2  06-72 

110 

2  27-39 

120 

2  48-06 

130 

2  68-73 

140 

2  89-41 

\ 

2  07-75 

£ 

2  28-42 

I 

2  49-10  j 

i 

2  69-77 

1 

2  90-44 

101 

2  08-79 

111 

2  29-46 

121 

2  50-13 

131" 

2  70-80 

141 

2  91-47 

ft 

2  09-82 

£ 

2  30  49 

l 

2  51-16  |       ft 

2  71-83 

JT  2  92-51 

102 

2  10-85 

112 

2  31-52 

122 

2  52-20 

132 

2  72-87 

142  j  2  93-54 

ft 

2  11-89 

1 

2  32-56 

l 

2  53-23 

ft 

2  73-90 

ft!  2  94-57 

103" 

2  12-92 

113' 

2  33-59 

123' 

2  54-26 

133" 

2  74-94 

143" 

2  95-61 

i 

2  13-95 

i 

2  34-63 

ft 

2  55-30; 

£ 

2  75-97 

ft 

2  96-64 

104 

2  14-99 

114 

2  35-66 

124 

2  56-33  j 

134 

2  77-00 

144" 

2  97-67 

ft 

2  16-02 

ft 

2  36-69 

£ 

2  57-36 

ft 

2  78-04 

i 

2  98-71 

105 

2  17-05 

115 

2  37-73 

125" 

2  58-40  | 

135" 

2  79-07 

145" 

2  99-74 

i 

2  18-09 

1 

2  38-76 

l 

2  59-43 

^ 

2  80-10 

ft 

3  00-78 

106 

2  19-12 

116 

2  39-79 

126' 

2  60-46 

136'" 

2  81-14 

146" 

3  01-81 

i 

2  20-16 

l 

2  40-83 

£ 

2  61-50' 

.j. 

2  82-17 

i 

3  02-84 

L07' 

2  21-19 

117 

2  41-86 

127 

2  62-53 

137' 

2  83-20 

147' 

3  03-88 

ft 

2  22-22 

^ 

2  42-89 

l 

2  63-57  ' 

i 

2  84-24 

1 

3  04-91 

108" 

2  23-26 

118 

2  43-93 

128 

2  64-60 

138" 

2  85-27 

148" 

3  05-94 

i 

2  24-29 

2  44-96 

ft 

2  65-63 

£ 

2  86-30 

Jf 

3  06-98 

109 

2  25-32 

119' 

2  45-99 

129 

2  66-67 

139 

2  87-34 

149 

3  08-01 

* 

2  26-36 

ft 

2  47-03 

ft 

2  67-70 

ft 

2  88-37 

ft 

3  09-04 

q 

1       3 

q 

1       3 

2 

1      5 

a 

1     | 

• 

2        . 

s 

?      s 

Q        ° 

s 
S 

1       o 

& 

1       * 

£ 

1     <3 

K 

1  i 

150 

3  10-08 

160 

3  30-75 

170 

3  51-42 

180 

3  72-09 

190 

3  92-76 

i 

3  11-11 

i 

3  31-78 

\ 

3  52-45 

\ 

3  73-13 

ft!  3  93-80 

151 

3  12-14 

161 

3  32  82 

171 

3  53-49 

181 

3  74-16 

191 

3  94-83 

ft 

3  13-18 

'   i 

3  33-85 

i 

3  54-52 

ft 

3  75-19 

i 

3  95-87 

152" 

3  14-21 

162 

3  34-88 

172 

3  55-56 

182 

3  76-23 

192 

3  96-90 

i 

3  15-25 

i 

3  35-92 

\ 

3  56-59 

ft 

3  77-26 

k 

3  97-93 

153 

3  16-28 

163 

3  36-95 

173 

3  57-62 

183" 

3  78-29 

193     3  98-97 

i 

3  17-31 

ft 

3  37-98 

ft 

3  58-66 

i 

3  79-33 

\.  4  00-00 

154 

3  18-35 

164 

3  39-02 

174 

3  59-69 

184 

3  80-36 

194 

4  01-03 

i 

3  19-38 

ft 

3  40-05 

i 

3  60-72 

k 

3  81-40 

\ 

4  02-07 

155 

3  20-41 

165 

3  41-09 

175 

3  61-76 

185 

3  82-43 

195 

4  03-10 

ft 

3  21-45 

^  3  42-12 

ft 

3  62-79 

* 

3  83-46 

k 

4  04-13 

156 

3  22-48 

166"!  3  43-15 

176 

3  63-82 

186 

3  84-50 

196     4  05-17 

i 

3  23-51 

ft{3  44-19 

i 

3  64-86 

ft 

3  85-53 

%  4  06-20 

157 

3  24-55 

167"!  3  45-22    177" 

3  65-89 

187 

3  86-56 

197 

4  07-24 

i 

3  25-58 

ftj  3  46-25 

|  3  66-93 

1       \ 

3  87-60 

i 

4  08-27 

158 

3  26-61 

168" 

3  47-29 

178" 

3  67-96 

188 

3  88-63 

198":  4  09-30 

i 

3  27-65 

i 

3  48-32 

| 

3  68-99 

!      * 

3  89-66 

£  4  10-34 

159 

3  28-68 

169" 

3  49-35 

179 

3  70-03 

189" 

3  90-70 

199     4  11-37 

i 

3  29-72 

£J3  50-39 

i 

3  7106 

i     i 

3  91-73J!       i:4  12-40 

PART  IV.   VALUE   OF  GOLD  IN   THE   U.S.   OF  AMERICA.     197 


Table  of  the  Value  of  Gold — continued. 


__ 

1     1 

0> 

& 

S 

1    s 

| 

I    1 

1 

1    1 

1 

1  i 

200 

4  13-44 

210 

4  34-11  !220 

4  54-78 

230 

4  75-45 

240 

4  96-12 

£ 

4  14-47 

!  4  35-14  i       £ 

4  55-81 

i 

4  76-49 

i 

4  97-16 

201 

4  15-50 

211"  4  36-18   221 

4  56-85 

231 

4  77-52 

241 

4  98-19 

i 

4  16-54 

^  4  37-21  I!       ^ 

4  57-88 

i 

4  78-55 

i 

4  99-22 

202 

4  17-57 

212  :4  38-24   222 

4  58-91    232" 

4  79-59 

242 

5  00-26 

i  4  18-60 

i  4  39-28  !        i 

4  59-95 

&  4  80-62 

i 

5  01-29 

203 

4  19-64 

213" 

4  40-31  ;  223 

.  4  60-98  :233" 

4  81-65  f 

243' 

5  02-33 

i  4  20-67 

£  4  41-34 

4  62-02  j|       |  4  82-69 

i 

5  03-36 

204" 

4  21-71 

214"   4  42-38   224" 

4  63-05    234     4  83-72 

244' 

5  04-39 

i 

4  22-74 

i  4  43-41 

J 

1  4  64-08 

£;  4  84-75 

I 

5  05-43 

205 

4  23-77 

215     4  44-44    225 

4  65-12 

235 

4  85-79 

245 

5  06-46 

i 

4  24-81 

1 

4  45-48 

i 

4  66-15 

i  4  86-82 

i 

5  07-49 

206 

4  25-84 

216 

4  46-51    226" 

|4  67-18 

236" 

4  87-86 

246 

5  08-53 

^. 

4  26-87 

£ 

4  47-55  I       | 

4  68-22 

^  4  88-89 

* 

5  09-56 

207" 

4  27.-91 

217     4  48-58   227" 

i  4  69-25 

'237 

4  89-92 

247 

5  10-59 

£ 

4  28-94 

^  4  49-61  i|       \ 

4  70-28  |       £  4  90'96 

i 

5  11-63 

208 

4  29-97 

218 

4  50-65   228 

4  71-32 

238 

4  91-99 

248 

5  12-66 

i 

4  31-01 

i 

4  51-68 

4 

-  4  72-35 

£  4  93-02 

1 

5  13-70 

209 

4  32-04 

219 

4  52-71    229 

4  73-39 

239 

4  94-06 

249 

5  14-37 

2 

4  33-07 

£ 

4  53-75 

i 

4  74-42 

2 

4  95-09 

* 

5  15-76 

<a 
£ 

i  3 

1  <B 

1 

1   1 

§   5 

3J 

5 

1   1 

S  ^  | 

2 
S 

1   * 
I   3 

a 
S 

1  i 

250 

5  16-80  260 

5  37-47  ; 

270 

5  58-14 

280 

5  78-81 

290 

5  99-48 

i 

5  17-83  !   £ 

5  38-50 

^ 

5  59-17 

±  5  79-84 

i 

6  00-52 

251 

5  18-86  261 

5  39-53 

271 

5  60-21 

281 

5  80-88  1291 

6  01-55 

i 

5  19-90 

i 

5  40-57  , 

i 

5  61-24 

$  5  81  '91 

* 

6  02-58 

252" 

5  20-93  262 

5  41-60 

272 

5  62-27 

282 

5  82-95  292 

6  03-62 

I 

5  21-96    | 

5  42-64 

* 

5  63-31 

|!  5  83-98 

* 

6  04-65 

253 

5  23-00  263 

5  43-67  !273~ 

5  64-34 

283 

5  85-01 

293 

6  05-68 

i 

5  24-03    i 

5  44-70    £ 

5  65-37 

i 

5  86-05 

•i 

6  06-72 

254 

5  25-06  264 

5  45-74  274 

5  66-41 

284 

5  87-08 

294 

6  07-75 

I 

5  26-10 

il  5  46-77  !l   ^ 

5  67-44 

£!5  88-11 

* 

6  0879 

255 

5  27-13  265" 

5  47-80  275 

5  68-48 

285 

5  89-15 

295 

6  09-82 

i 

5  28-17 

i 

5  48-84 

i 

5  69-51 

1 

5  90-18 

i 

6  10-85 

256 

5  29-20  266 

5  49-87 

276 

5  70-54 

286 

5  91-21 

296 

6  11-89 

i 

5  30-23 

i 

5  50-90 

i 

5  71-58 

i 

5  92-25 

i 

6  12-92 

257 

5  31-27  267 

5  51-94 

277 

5  72-61 

287 

5  93-28  297" 

6  13-95 

1 

5  32-30    |!  5  52-97 

* 

5  73-64 

£l  5  94-32 

fj  6  14-99 

258" 

5  33*33  1268 

5  54-01 

278 

5  74-68 

288 

5  95-35 

298" 

6  16-02 

* 

5  34-37    £ 

5  55-04 

i 

5  75-71 

£  5  96-38 

i 

6  17-05 

259 

5  35-40  269 

5  56-07  1279 

5  76-74 

289  i  5  97-42  !  299" 

6  18-09 

i 

5  36-43 

i 

5  57-11  j   * 

5  77-78 

£  5  98-45 

i 

6  19  12 

198   ENGLISH   AND   AMERICAN   VALUES   OF   GOLD.  PART  IV. 


Table  of  the  Value  of  Goli — continued. 


0> 

P     a 

2 

I       | 

<a 

1      5 

a> 

1       3 

2 

3        ti 

g 

1     3 

S 

o       ^ 

1 

ft      S 

I 

1       <§ 

& 

1    <s 

300 

6  20-16 

310 

6  40-83 

320 

6  61-50 

330 

6  82-17 

340 

7  02-84 

4 

6  21-19 

* 

6  41-86 

* 

6  62-53 

* 

6  83-20 

* 

7  03-88 

301 

6  22-22 

•311 

6  42-89 

321 

6  63-57 

331 

6  84-24 

341 

7  04-91 

1 

6  23-26 

* 

6  43-  y  3 

k 

6  64-60 

* 

6  85-27 

2 

7  05-94 

302 

6  24-29 

312 

6  44-96 

322 

6  65-63 

332 

6  86-30 

342     7  06-98 

i 

6  25-32 

i 

6  45-99 

1 

6  66-67 

^ 

6  87-34 

±  7  08-01 

303" 

6  26-36 

313" 

6  47-03 

323^ 

6  67-70 

3331 

6  88-37 

343" 

7  09-04 

i 

6  27-39 

* 

6  48-06 

.J. 

6  68-73 

£ 

6  8941 

i  7  10-08 

304 

6  28-42 

314 

6  49-10 

324" 

6  69-77 

334 

6  90-44    344"  7  11-11 

i 

6  29-46 

1 

6  50-13 

1 

6  70-80 

* 

6  91-47  1       i  7   12-14 

305 

6  30-49 

315" 

6  51-16 

325" 

6  71-83 

335 

6  92-51    345"  7  13-18 

* 

6  31-52 

} 

6  52-20 

} 

6  72-87 

A!  6  93-54 

f  7  14-21 

306 

6  32-56 

316 

6  53-23 

326 

6  73-90 

336" 

6  94-57 

346     7  15-25 

* 

6  33-59 

£|  6  54-26 

k 

6  74-94 

£  6  95-61 

£  7  16-28 

307 

6  34-63 

317 

6  55-30 

327 

6  75-97 

337 

6  96  64 

347     7  17-31 

* 

6  35-66 

* 

6  56-33 

^ 

6  77-00 

1 

6  97-67 

f  7  18-35 

308 

6  36-69 

318" 

6  57-36 

328" 

6  78-04 

338L 

6  98-71 

348  I  7  19-38 

* 

6  37-73 

1 

6  58-40 

* 

6  79-07 

| 

6  99-74 

f  7  20-41 

309 

6  38-76 

319' 

6  59-43 

329 

6  80-10 

339' 

7  00-78 

349     7  21-45 

* 

6  39-79 

* 

6  60-47 

* 

6  81-14 

'    * 

7  01-81 

£  7  22-48 

2 

1   1 

j 

1   5 

I 

1   3 

2 

S  a 

2 

1   5 

E 

S   o 

1 

1  3 

£ 

1  3 

K 

a  « 

£ 

1   1 

350 

7  23-51 

360 

7  44-19 

370 

7  64-86 

380 

7  85-53 

390 

8  OiV20 

i 

7  24-55 

* 

7  45-22 

* 

7  65-89 

I 

7  86-56 

| 

8  07-24 

351 

7  25-58 

361 

7  46-25 

371 

7  66-93 

381 

7  87-60 

391" 

8  08-27 

* 

7  26-61 

* 

7  47-29 

$ 

7  67-96 

i 

7  88-63 

* 

8  09-30 

352 

7  27-65 

362" 

7  48-32 

372 

7  68-99 

382 

7  89-66 

392" 

8  10-34 

* 

7  28-68 

i 

7  49-35 

i 

7  70-03 

i 

7  90-70 

* 

8  11-37 

353 

7  29-72 

363" 

7  50-39 

373 

7  71-06 

383 

7  91-73 

393 

8  12-40 

* 

7  30-75 

$ 

7  51-42 

| 

7  72-09 

| 

7  92-76 

A 

8  13-44 

354 

7  31-78 

364" 

7  52-45 

374 

7  73-13 

384 

7  93-80 

894 

8  14-47 

* 

7  32-82 

i 

7  53-49 

| 

7  74-16 

i 

7  94-83 

$ 

8  15-50 

355 

7  33-85 

365 

7  54-52 

375 

7  75-19 

385 

7  95-87 

395 

8  16-54 

} 

7  34-88 

$ 

7  55-56 

A 

7  76-23 

| 

7  96-90 

| 

8  17-57 

356 

7  35-92 

366 

7  56-59 

376 

7  77-26 

386 

7  97-93 

396 

8  18-60 

* 

7  36-95 

} 

7  57-62 

4 

7  78-29 

* 

7  98-97 

i 

8  19-64 

357 

7  37-98 

367 

7  58-66 

377 

7  79-32 

387 

8  00-00 

397" 

8  20-67 

* 

7  39-02 

1 

7  59-69 

| 

7  80-36 

£ 

8  01-03 

| 

8  21-71 

358 

7  40-05 

368' 

7  60-72 

^78" 

7  81-39 

388 

8  02-07 

398"  j 

8  22-74 

* 

7  41-09 

$ 

7  61-76 

| 

7  82-43 

$ 

8  03-10 

i' 

8  23-77 

359 

7  42-12 

369 

7  62-79 

379* 

7  83-46 

389 

8  04-13 

399  | 

8  24-81 

i 

7  43-15 

* 

7  63-82 

* 

7  84-50 

1 

8  05-17  : 

| 

8  25-84 

PART  IV.    VALUE  OF  GOLD   IN  THE  U.S.   OF  AMEKICA.     199 
Table  of  the  Value  of  Gold — continued. 


1 

s 

1   1 
1   ^ 

1 

«3 
c3     +-> 

2 

i 

I  1 

2 

£ 

2   5 

1  1 

o 

£ 

1  2 
1  & 

400 

8  26-87 

410 

8  47-55 

'420 

8  68-22 

430 

8  88-89 

440 

9  09-56 

£  8  27-91 

£ 

8  48-58 

£ 

8  69-25 

* 

8  89-92 

* 

9  10-59 

401 

8  28-94 

411 

8  49-61 

421 

8  70-28 

431 

8  90-96 

441 

9  11-63 

^ 

8  29-97 

i 

8  50-65  |   £ 

8  71-32 

\ 

8  91-99 

i 

9  12-66 

402" 

8  31-01 

412 

8  51-68  422 

8  72-35 

432 

8  93-02 

442 

9  13-70 

* 

8  32-04 

* 

8  52-71 

i 

8  73-39 

£ 

8  94-06 

\ 

9  14-73 

403 

8  33-07 

413 

8  53-75 

423 

8  74-42 

433 

8  95-09 

443 

9  15-76 

* 

8  34-11 

£ 

8  54-78 

i 

8  75-45 

£ 

8  96-12 

k 

9  16-80 

404 

8  35-14 

414 

8  55-81 

424 

8  76-49 

434 

8  97-16 

444 

9  1783 

* 

8  36-18    £ 

8  56-85  |   £ 

8  77-52 

i 

8  98-19 

* 

9  18-86 

405 

8  37-21 

415 

8  57-88  425 

8  78-55 

435 

8  99-22 

445 

9  19-90 

£ 

8  38-24 

£ 

8  58-91 

i 

8  79-59 

£ 

9  00-26 

i 

9  20-93 

406" 

8  39-28 

416 

8  59-95 

426 

8  80-62 

436 

9  01-29 

446 

9  21-96 

* 

8  40-31 

£ 

8  60-98 

£ 

8  81-65 

£ 

9  02-33 

£ 

9  23-00 

407 

8  41-34 

417 

8  62-02 

427 

8  82-69 

437 

9  03-36 

447 

9  24-03 

| 

8  42-38 

£ 

8  63-05 

£ 

8  83-72 

\ 

9  04-39 

i 

9  25-06 

408 

8  43-41 

418 

8  64-08  428" 

8  84-75 

438 

9  05-43 

448 

9  26-10 

* 

8  44-44 

i 

8  65-12 

£ 

8  85-79 

£ 

9  06-46 

i 

9  27-13 

409  8  45-48 

419 

8  66-15  429" 

8  86-82 

439 

9  07-49 

449 

9  28-17 

i 

8  46-51 

\ 

8  67-18    £ 

8  87-86 

} 

9  08-53 

\ 

9  29-20 

8 

s 

1    1 
1    * 

2 

£ 

1   1 
1   * 

2 
1 

|   | 
1   S 

<D 

1  1 

1 

1   " 

1  1 

450 

9  30-23 

460 

9  50-90 

470 

9  71-58 

480 

9  92-25 

490 

10  12-92 

i 

9  3127 

i 

9  51-94 

* 

9  72-61 

* 

9  93-28 

\ 

10  13-95 

451 

9  32-30 

461 

9  52-97 

471 

9  73  64 

481 

9  94-32 

491 

10  14-99 

£ 

9  33-33 

^ 

9  54-01 

^ 

9  74-68 

^ 

9  95-35 

£ 

10  16-02 

452 

9  34-37 

462 

I)  55-04 

472 

9  75-71 

482 

9  96-38 

492 

10  17-05 

£ 

9  35-40 

i 

9  56-07 

i 

9  76-74 

* 

9  97-42 

i 

10  18-09 

453 

9  36-43 

463 

9  57-11 

473 

9  77-78 

483 

9  98-45 

493 

10  19-12 

£ 

9  37-47 

| 

9  58-14 

i 

9  78-81 

\ 

9  99-48 

£ 

10  20-16 

454 

9  38-50 

464 

9  59-17 

474 

9  79-84 

484  |10  00-52 

494 

10  21-19 

^ 

9  39-53 

k 

9  60-21 

^ 

9  80-88 

£10  01-55 

£ 

10  22-22 

455 

9  40-57 

465 

9  61-24 

475 

9  81-91 

485  10  02-58 

495" 

10  23-26 

* 

9  41-60 

i 

9  62-27 

\ 

9  82-95 

i!lO  03-62 

£ 

10  24-29 

456 

9  42-64 

466 

9  63-31 

476 

9  83-98 

486  10  04-65 

496 

10  25-32 

i 

9  43-67 

i 

9  64-34 

\ 

9  85-01 

ilO  05-68 

£ 

10  26-36 

457 

9  44-70 

467 

9  65-37 

477 

9  86-05 

487  !10  06-72 

,497 

10  27-39 

i 

9  45-74 

| 

9  66-41 

^ 

9  87-08 

£10  07-75J   £ 

10  28-42 

458  |  9  46-77 

468 

9  67-44 

478 

9  88-11 

488  ilO  08-79  498 

10  29-46 

A!  9  47-80 

i 

9  68-48 

^- 

9  89-15 

£10  09-82=   £ 

10  30-49 

459 

9  48-84 

469 

9  69-51 

479 

9  90-18 

489  10  10-85  499 

10  31-52 

i 

-2 

9  49-87 

* 

9  70-54 

* 

9  91-21 

£10  11-89   £,10  32-56 

200   ENGLISH  AND   AMERICAN  VALUES   OF   GOLD.   PART  IV. 


Table  of  the  Value  of  Gold—  continued. 


I 

1   1 

^   o 

P 

1 
£ 

2J       * 

I  S 

1 

1  | 

1 

1   1 

E 

1   % 
1   <§. 

500 

10  33-59!  510 

10  54-26 

520 

10  74-94 

530 

10  95-61 

540 

11  16-28 

£10  34-631   £ 

10  55-30 

£ 

10  75-97 

£10  96-64 

£ 

11  17-31 

501  10  35-66  1511 

10  56-33 

521 

10  77-00 

531  10  97-67 

541 

11  18-35 

£110  36-69 

£ 

10  57-36 

± 

10  78-04 

±10  98-71 

£ 

11  19-38 

502  10  37-73 

512 

10  58-40 

522 

10  79-07 

532  |10  99-74 

542 

11  20-41 

±10  38-76 

i 

10  59-43 

£ 

10  80-10 

±11  00-78 

£ 

11  21-45 

503"  10  39-79 

513 

10  60-47 

523 

10  81-14 

533  [11  01-81 

543 

11  22-48 

±10  4083 

£ 

10  61-50 

£ 

10  82-17 

£11  02-84 

i 

11  23-51 

504  |10  41-86 

514 

10  62-53 

524 

10  83-20 

534  11  03-88 

544" 

11  24-55 

±  10  42-89 

± 

10  63-57 

£ 

10  84-24 

£11  04-91 

£ 

11  25-58 

505  10  43-93 

515 

10  64-60 

525 

10  85-27, 

636  11  05-94 

545 

11  26-61 

£10  44-96 

£ 

10  65-63 

£ 

10  86-30 

£lll  06-98 

£ 

11  27-65 

506"!  10  45-99 

516 

10  66-67 

526 

10  87-34i 

536  11  08-01 

546 

11  28-68 

£  10  47-03 

± 

10  67-70 

£ 

10  88-37 

£11  09-04 

£ 

11  29-72 

507  10  48-06 

517" 

10  68-73 

527 

10  89-41 

537 

11  10-08 

547 

11  30-75 

£110  49-10 

£ 

10  69-77 

£ 

10  90-44 

£jll  11-11 

£ 

11  31-78 

508  10  50-13 

518 

10  70-80 

528 

10  91-471 

538  11  12-14 

548 

11  32-82 

£10  51-16 

£ 

10  71-83 

± 

10  92-51 

£ 

11  13-18 

i 

11  33-85 

509 

10  52-20 

519 

10  72-87  529" 

10  93-54 

539 

11  14-21 

549'" 

11  34-88 

* 

10  53-23 

±10  73-90 

* 

10  94-57 

* 

11  15-25 

* 

11  35-92 

a 

1  | 

S 

1   1 

§ 

1   1 

i 

I   45 

j 

i   5 

£ 

I  ! 

£ 

2  1 

S 

1   § 
n   o 

£ 

1   J 

E 

1   1 

550 

11  36-95 

560 

11  57-62 

570 

11  7S29 

580 

11  98-97 

5<)0 

12  19-64 

£ 

11  37-98 

£ 

11  58-66 

£ 

11  79^ 

£ 

12  00-00 

£ 

12  20-67 

551 

11  39-02 

561 

11  59-69 

571 

11  80  d^  581" 

12  01-03 

591 

12  21-71 

£11  40-05 

£ 

11  60-72 

£ 

11  81'4°J   £ 

12  02-07: 

£ 

12  22-74 

552  ill  41-09 

562 

11  61-76 

572 

11  82-43,582 

12  03-10  592 

12  23-77 

£11  42-12 

£ 

11  62-79 

£ 

11  83-46   ± 

12  04-13'   £ 

12  24-81 

553 

11  43-15 

563 

11  63-82 

573 

11  84-50  '583 

12  05-17  593" 

12  25-84 

£ 

11  44-19 

£ 

11  64-86 

£ 

11  85-53i   £ 

12  06-20 

£ 

12  26-87 

554 

11  45-22 

564 

11  65-89 

574 

11  86-56  584  12  07-24 

594 

12  27-91 

£11  46-25 

£ 

11  66-93 

_£ 

11  87-60;   £ 

12  08-27 

£ 

12  28-94 

555 

11  47-2^1 

565  ill  67-96 

575 

11  88-63  585 

12  09-30 

595 

12  29-97 

£ 

11  48-32 

£11  68-99 

£ 

11  89-06 

I 

12  10-34 

i 

12  31-01 

556 

11  49-35 

566 

11  70-03 

576 

11  90-70:586" 

12  11-37 

596 

12  32-04 

£ 

11  50-39 

£ 

11  71-06 

_£ 

11  91-73 

i 

12  12-40 

£ 

12  33-07 

557 

11  51-42 

567  |11  72-09 

577 

11  92-76 

587" 

12  13-44 

597 

12  34-11 

£ 

11  52-45 

£11  73-13 

£ 

11  93-80 

i 

12  14-47 

£ 

12  35-14 

558  ill  53-49 

568  11  74-16 

578 

11  94-83! 

588" 

12  15-50 

598 

12  36-18 

£11  54-52 

£ 

11  75-19 

£ 

11  95-87 

£ 

12  16-54 

£ 

12  37-21 

559 

11  55-56 

569  11  76-23 

579 

11  96-90 

589 

12  17-57 

599 

12  38-24 

£ 

11  56-59 

£11  77-26 

i 

11  97-93 

i 

12  18-60 

t 

12  39-28^ 

PART  IV.  VALUE  OF  GOLD  IN  THE  U,S,   OF  AMERICA.    201 


Table  of  the  Value  of  Gold— continued. 


8 

£ 

1   A 

=3    § 
ft   o 

9i 
.5 

K 

1   S 
=3   3 

ft  0 

2    c3     -2 

s  1  | 

<u 

1  ! 

o   " 

| 

£ 

I  4 
1  3 

600 

12  40'31 

610 

12  60*98  620  12  81'65 

630 

13  02'33 

640 

13  23-00 

i 

12  41'34 

* 

12  62-02 

£12  82-69 

* 

13  03-36 

* 

13  24-03 

601 

12  42-38 

611 

12  63-05 

621  12  83-72 

631 

13  04-39 

641 

13  25-06 

£ 

12  43-41 

£12  64-08    £12  84-75 

* 

13  05-43 

* 

13  26-10 

602" 

12  44-44 

612  12  65-12:622  12  85'79 

632 

13  06-46 

642 

13  27-13 

i 

12  45-48 

4rl2  66*16   £12  86-82 

£ 

13  07-49 

£ 

13  28  17 

603 

12  46-51 

613~J12  67'18  623  12  87-86 

633 

13  08-53 

643 

13  29-20 

* 

12  47-55 

£12  68-22)   £12  88-89 

* 

13  09-56 

* 

13  30-23 

604 

12  48-58 

614 

12  69-25  624  12  89'92 

634 

13  10-59 

644 

13  31-27 

* 

12  49-61 

£ 

12  70-28 

£12  90-96 

£ 

13  11-63 

£ 

13  32-30 

605 

12  50-65 

615 

12  71-32 

625  12  91-99 

635" 

13  12-66 

645 

13  33-33 

i 

12  51-68 

} 

12  72-35 

£12  93-02 

£ 

13  13-70 

i 

13  34-37 

606 

12  52-71 

616 

12  73-39 

626  12  94-06 

636 

13  14-73 

646 

13  35-40 

* 

12  53-75 

£ 

12  74-42 

£12  95-09 

£ 

13  15-76 

* 

13  36-43 

607 

12  54-78 

617 

12  75-45 

627  12  96-12 

637 

13  16-80 

647 

13  37'47 

i 

12  65-81! 

£ 

12  76-49 

£12  97-16 

£ 

13  17-8311   £ 

13  38-50 

608" 

12  56-85 

618 

12  77-52 

628"  12  98-19 

638"  13  18-86 

648 

13  39-53 

* 

12  57-88' 

* 

12  78-55 

£12  99-22 

£13  19-90 

£ 

13  40-57 

609  |12  58-91 

619  ,12  79-59 

629  13  00-26 

639  13  20-93 

649 

13  41-60 

1 

12  59-95 

£12  80-62 

£13  01-29 

£13  21-96!l   £ 

13  42-64 

g 

i 

1   1 

a  o 

1 

1   A 
1   1 

1 

I  1 

ft   ^ 

I 

J.8 
i 

ft    « 

0> 

1   .2 

^j     S 
p    CJ> 

650  13  43-67 

660  13  64-33 

670  13  85-01 

680 

14  05-68 

690 

14  26-86 

£13  44-70 

£13  65-37 

£|13  86-05 

i 

2 

14  06-72 

£ 

14  27-39 

651  13  45-74 

661  i!3  66-41 

671 

13  87-08 

681 

14  07-75  691 

14  28-42 

£13  46-77 

£13  67-44 

£ll3  88-11 

£ 

14  08-79   £ 

14  29-46 

652 

13  47-80 

662  |13  68'48 

672  13  89-15 

682 

14  09-82  692 

14  30-49 

£13  48-84 

£13  69-51 

£ 

13  90-18 

* 

14  10-85||   £ 

14  31-52 

653  :13  49-871  663"  13  70'54 

673  13  91-21 

683 

14  11-89 

693 

14  32-56 

£13  50-90|   £13  71-58 

£13  92-25 

£ 

14  12-92 

\ 

14  33-59 

654 

13  51-94  664 

13  72«61 

674  113  93-28 

684 

14  13-95 

694 

14  34-63 

£13  52-97 

£13  73-64 

£13  94-3'2 

£ 

14  14-99 

1 

14  35-66 

655  13  54-01  665~|13  74'68 

675 

13  95'35 

685 

14  16-02 

695 

14  36-69 

£|13  55-04 

£,13  75-71 

£ 

13  96-38 

£ 

14  17-05 

£ 

14  37-73 

656"  |13  56-07 

666  |l3  76-74 

676 

13  97'42 

686 

14  18-09 

696 

14  38-76 

£13  57-11 

£ 

13  77-78 

* 

13  98-45 

% 

14  19-12 

i 

14  39-79 

657" 

13  58-14  667 

13  78-81 

677 

13  99'48 

687 

14  20-16 

697 

14  40-83 

£ 

.13  59-17 

£13  79-84 

£ 

14  00-52 

£ 

14  21-19 

£ 

14  41-86 

658 

13  60-21  668" 

13  80-88 

678" 

14  01-55 

688 

14  22-22 

698 

14  42-89 

* 

13  61-24 

* 

13  81-91 

* 

14  02-58 

£ 

14  23-26 

\ 

14  43-93 

659 

13  62-27 

669 

13  82-95 

679 

14  03-62 

689 

14  24-29 

699 

14  44-96 

* 

13  63-31 

£ 

13  83-98 

i 

14  04-65 

£ 

14*  25-32 

\  14  45-99 

202   ENGLISH  AND  AMERICAN  VALUES   OF   GOLD.   PABT  IV, 
Table  of  the  Value  of  Gold— continued. 


I 

1   1 
§   3 

§ 

£ 

1   * 
"o    § 
Q   O 

1 

I   3 
1   * 

§ 
£ 

I  i 

a 
S 

1   1 
1  3 

700 

14  47-03 

710 

14  67-70 

720 

14  88-37 

730 

15  09-04 

740 

15  29-72 

* 

14  48-06 

* 

14  68-73 

1   i 

14  89-41 

* 

15  10-08 

tH5  30-75 

701 

14  49-10 

711 

14  69-76 

721 

14  90-44 

731 

15  11-11 

741" 

15  31-78 

* 

14  50-13 

* 

14  70-80 

* 

14  91-47 

i 

15  12-14 

i 

15  32-82 

702 

14  51-16 

712 

14  71-83 

722 

14  92-51 

732 

15  13-18 

742  115  33-85 

i 

14  52-20 

* 

14  72-87 

i   £ 

14  93-54 

1 

15  14-21 

i 

15  34-88 

703 

14  53-23 

713  14  73-90 

723 

14  94-57 

733 

15  15-25 

743 

15  35-92 

i 

14  54-26 

114  74-94 

? 

14  95-61 

i 

15  16-28 

i 

15  36-95 

704 

14  55-30 

714 

14  75-97 

724 

14  96-64 

734 

15  17-31 

744 

15  37-98 

* 

14  56-33 

* 

14  77-00 

\ 

14  97-67 

i 

15  18-35 

i 

15  39-02 

705 

14  57-36 

715 

14  78-04 

'725 

14  98-71 

735 

15  19-38 

745 

15  40-05 

\ 

14  58-40 

i 

14  7907 

\ 

14  99-74 

£ 

15  20-41 

i 

15  41-09 

706 

14  59-43 

716 

14  80-10 

,726 

15  00-78 

736  15  21-45 

746 

15  42-12 

* 

14  60-47 

* 

14  81-14 

\ 

15  01-81 

115  22-48 

i 

15  43-15 

707 

14  61-50 

717 

14  82-17 

727 

15  02-84 

737  16  23-51 

747 

15  44-18 

* 

14  62-53 

* 

14  83-20 

"2 

15  03-88 

1 

15  24-55 

-j 

15  45-22 

708 

14  63-57 

718  114  84-24 

'728 

15  04-91 

738 

15  25-58 

748 

15  46-25 

\ 

14  64-60 

£14  85-27 

1  15  05-94 

i 

15  26-61 

-* 

15  47-29 

709 

14  65-63 

719  !l4  86-30 

729  15  06-98 

739 

15  27-65 

749 

15  48-32 

\ 

14  66-67 

£14  87-84  1   115  08-01 

115  28-68 

115  49-35 

1 

2    w 

1  I 

§ 
£ 

Dollars 
Cents 

1 

1  ! 

Q 

1 

1  i 

8 

R 

a   o 

750 

15  50-39 

760 

15  71-06 

770 

15  91-73 

780 

16  12-40 

790 

16  33-07 

i 

15  51-42 

i 

15  72-09 

1 

15  92-76 

i 

16  13-44 

£ 

16  34-11 

751 

15  52-45 

761 

15  73-13 

771 

15  93-80 

781 

16  14-47 

791  |16  35-14 

£ 

15  53-49 

| 

15  74-16 

£ 

15  94-83 

i 

16  15-50 

116  36-18 

752 

15  54-52 

762 

15  75-19 

772 

15  95-87 

782" 

16  16-54 

792"|16  37-21 

i 

15  55-56 

i 

15  76-23 

l 

15  96-90 

i 

16  17-57 

116  38-24 

753' 

15  56-59 

763" 

15  77-26 

773  15  97-93 

783' 

16  18-60 

793"  16  39-28 

i 

15  57-62 

* 

15  78-29 

115  98-97 

i 

16  19-64 

£16  40-31 

754 

15  58-66 

764 

15  79-33 

774  |16  OO-Ooi'784 

16  20-67 

794  16  41-34 

i 

15  59-69 

i;i5  80-36 

£16  01-03   £ 

16  21-71 

116  42-38 

755' 

15  60-72 

765 

15  81-40 

775  16  02-07!  785 

16  22-74 

795  J16  43-41 

£ 

15  61-76 

£ 

15  82-43 

116  03-10|!   i 

16  23-77 

i!16  44-44 

756 

15  62-79 

766 

15  83-46 

776  il6  04-131,786 

16  24-81 

796 

16  45-48 

i 

15  63-82 

i 

15  84-50 

116  05-17   £ 

16  25-84 

* 

16  46-51 

757 

15  64-86 

767 

15  85-53 

777  16  06-20;:787 

16  26-87 

797 

16  47-55 

i 

15  65-89 

£ 

15  86-56 

1  16  07-24 

i 

16  27-91 

£ 

16  48-58 

758 

15  66-93 

768 

15  87-60 

778  16  08-27 

788' 

16  28-94 

798' 

16  49-61 

i 

15  67-96 

i 

15  88-63 

116  09-30 

i. 

16  29-97 

i 

16  50-65 

759 

15  68-99 

769" 

15  89-66 

779  16  10-34 

789" 

16  31-01 

799" 

16  51-68 

* 

15  70-03 

* 

15  90-70 

116  11-37 

2 

16  32-04 

* 

16  52-71 

PAKT  IV.    VALUE  OF   GOLD  IN  THE  U.S.   OF  AMERICA.    203 


Table  oftlie  Value  of  Gold — continued. 


. 

I 

2       03 

1  EG 

o 

c3      ^    ' 

C> 

ci    OT 

© 

Q) 

cfl     -JS 

S 

o5     co 

£ 

1   1 

£ 

1  1 

1 

1  3 

(2 

£ 

1  1 

a 

£ 

1   i 

800 

16  53-75 

810 

16  £4-42 

!820 

16  95-09 

830 

17  15-70 

840 

17  36-43 

i 

16  54-78 

16  75-45    £ 

16  96-12 

£ 

17  16-80 

£17  37-47 

801 

16  55-81 

8112 

16  76-49  821 

16  97-16 

831 

17  17-83 

841  17  38-50 

i 

16  56-85 

£ 

16  77-52    £ 

16  98-19 

£ 

17  18-86 

£17  39-53 

802 

16  57-88 

812 

16  78-55 

822 

16  99-22 

832 

17  19-90 

842  !17  40-57 

i 

16  58-91 

£ 

16  79-59 

i 

17  00-26 

£ 

17  20-93 

£17  41-60 

803 

16  59-95 

813 

16  80-62 

823 

17  01-29 

833 

17  21-96 

843  17  42-64 

i 

16  60-98 

£ 

16  81-65 

£ 

17  02-33 

£ 

17  23-00 

J|17  43-67 

804 

16  62-02 

814 

16  82-69 

824 

17  03-36 

834 

17  24-03 

844 

17  44-70 

£ 

16  63-05 

£ 

16  83-72 

^ 

17  04-39 

£ 

17  25-06 

£ 

17  45-74 

805 

16  64-08 

815 

16  84-75 

1825 

17  05-43 

835 

17  26-10 

845 

17  46-77 

i 

16  65-12 

i 

16  85-79 

\ 

17  06-46 

I 

17  27-13 

£ 

17  47-80 

806 

16  66-15 

816 

16  86-82 

'826 

17  07-49 

836 

17  28-17 

846 

17  48-84 

£ 

16  67-18 

i 

16  87-86 

i 

17  08-53 

i 

L7  29-20 

i!l7  49-87 

807 

16  68-22 

817 

16  88-89 

827 

17  09-56 

837 

17  30-23 

847  17  50-90 

i 

16  69-25 

£ 

16  89-92 

£ 

17  10-59 

£ 

17  31-27 

£17  51-94 

808 

16  70-28 

818 

16  90-96 

828 

17  11-63 

838 

17  32-30 

848  17  52-97 

£ 

16  71-32 

£ 

16  91-99 

£ 

17  12-66 

£ 

17  33-33 

£17  54-01 

809 

16  72-35 

819 

16  93-02 

829 

17  13-70 

839 

17  34-37 

849  17  55-04 

* 

16  73-39 

* 

16  94-06 

£ 

17  14-73 

* 

17  35-40 

* 

17  56-07 

2 

1    -S 

£        05 

<£> 

CO 
tri       *£ 

1   -e 

£ 

£   » 

£ 

Q 

1 

1  ^ 

£ 

1   <§ 

c 

£ 

£  .  g 
p   ° 

a 

1  1 

850 

17  57-11 

860 

17  77-78 

870 

17  98-45 

880 

18  19-12 

890 

18  39-79 

£ 

17  58-14 

* 

17  78-81 

i 

17  99-48 

1 

18  20-16 

i 

18  40-83 

851 

17  59-17 

861 

17  79-84 

871 

18  00-52 

881 

18  21-19 

891 

18  41-86 

1 

17  60-21 

\ 

17  80-88 

]     i 

18  01-55 

£ 

18  22-22 

i 

18  42-89 

852 

17  61-24 

862 

17  81-91 

872 

18  02-58 

882 

18  23-26 

892' 

18  43-93 

4 

17  62-27 

J 

17  82-95 

i 

18  03-62 

i 

18  24-29 

i 

18  44-96 

853" 

17  63-31 

863 

17  83-98 

873 

18  04-65 

883 

18  25-32 

8932 

18  45-99| 

1 

17  64-34 

i 

17  85-01 

£ 

18  05-68 

-i 

18  26-36 

£ 

18  47-03 

854 

17  65-37 

864' 

17  86-05 

874 

18  06-72 

884 

18  27-39 

894 

18  48-06 

-| 

17  66-41 

i 

17  87-07 

i 

18  07-75 

i 

18  28-42 

i 

18  49-10 

855 

17  67-44 

865 

17  88-11 

875 

18  08-79 

885 

18  29-46 

895 

18  50-13 

i 

17  68-48 

£ 

17  89-15 

* 

18  09-82 

£ 

18  30-49 

£18  51-16 

856 

17  69-51 

866 

17  90-18 

876 

18  10-85 

886 

18  31-52 

896 

18  52-20 

i 

17  70-54 

i 

17  91-21 

i 

1       Q 

18  11-89 

i 

18  32-56 

i 

18  53-23 

857 

17  71-58 

867 

17  92-25 

877^ 

18  12-92 

887' 

18  33-59 

8972 

18  54-26 

i 

17  72-61 

^ 

17  93-28 

18  13-95 

i 

18  34-63 

i 

18  55-30 

858 

17  73-64 

868 

17  94-32 

8782 

18  14-99 

888 

18  35-66 

898' 

18  56-33 

3 

17  74-68 

i 

17  95-35 

i 

18  16-02 

i 

18  36-69 

i 

18  57-36 

859" 

17  75-71 

869 

17  96-38 

879 

18  17-05 

889' 

18  37-73 

899 

18  58-40 

« 

17  76-74 

A  17  97-42 

18  18-09 

£ 

18  38-76 

18  59-43 

204    ENGLISH  AND  AMERICAN  VALUES  OF  GOLD    PART  IV. 


Table  of  the  Value  of  Gold— continued. 


§ 
s 

!  I 

1 

1   1 
3   « 

1 

S  1 

1  a 

| 

1  1 

* 
m 

P   o 

900 

18  60-46 

010 

18  81-14 

920 

19  01-81 

980 

19  22-48 

940  19  43  15 

i 

18  61-50 

£ 

18  82-17 

£ 

19  02-84 

4 

19  23-51 

419  44-19 

901  2 

18  62-53 

911 

18  83-20 

921 

19  03-88  931" 

19  24-55 

941"  19  45-22 

£ 

18  63-57 

£ 

18  84-24 

£ 

19  04-91  i   4  19  25-58 

419  46-25 

902 

18  64-60 

912 

18  85-27  922 

19  05-94 

982 

19  26-61 

942"  j!9  47-29 

£ 

18  65-63 

£ 

18  86-30 

4 

19  06-98 

£ 

19  27-65 

£19  48-32 

903 

18  6667 

9L3 

18  87*84  J988" 

19  08-01 

933 

19  28-68 

943*  19  49-35 

£ 

18  67-70 

£ 

18  88-37   4 

L9  0904    419  29-72 

4 

19  50-39 

904 

18  68-73 

914 

18  89-41  1  924" 

19  1008  934"  19  30-75 

944" 

10  51-42 

£ 

18  69-77 

£ 

18  90-4411   £ 

19  11-11 

£19  81-78 

4  10  52-45 

905 

18  70-SO 

915 

18  91-47  925 

19  12-14:985" 

19  32-82 

945"  19  53-49 

£ 

18  71-83 

£ 

18  92-51 

£ 

19  13-18 

£  19  83-S5 

419  54-52 

906 

18  72-87 

916 

18  93-54 

926 

19  14-21 

936 

19  34-88 

946"  19  55-561 

£ 

18  73-90 

£ 

18  9457 

£ 

19  15-25 

1   * 

19  35-92 

4 

19  56-59 

907 

18  74-94 

917 

18  95-61 

927 

19  16-28 

937 

19  36-95 

947" 

19  57-62 

4 

18  75-97 

£ 

18  96-64 

£ 

19  17-31 

4 

19  37-98 

4 

19  58-66 

908 

18  77-00 

918 

18  97-67i928" 

19  18-35  938" 

19  39-02 

948 

19  59-69 

£18  78-04 

4 

18  98-71 

£19  1938]   £ 

19  40-05 

4 

19  60-72 

909  i!8  79-07 

919" 

18  99-74  929  19  20-41  939" 

19  41-08 

949" 

19  61-76 

£18  80-10 

£ 

19  00-78 

£19  21-45 

* 

19  42-12 

* 

19  62-79 

S 

I  5 

S 

1  * 

t 

I   f 

(U 

£  a 

2 

i  - 

£ 

1  3 

£ 

1  -  <§ 

i 

1  3 

S 

1   oS 

i 

1  1 

950 

19  63'82 

960 

19  84-50 

970 

20  05-17 

980 

20  25-8-1 

990 

20  46-51 

* 

19  64-86 

* 

19  85-53 

i 

20  06-20 

£ 

20  26-87  !   £ 

20  47-55 

951 

19  65-89 

961 

19  86-56 

971 

20  07-23 

981 

20  27-91  5)91" 

20  48-58 

£ 

19  66-93 

i 

19  87-60 

i 

20  08-27 

1 

20  28-9-1    J 

•20  49-61 

952 

19  67-96 

962 

19  88-63 

972 

20  09-30 

982 

20  29-97  992" 

20  50'65 

£ 

19  68-99 

£ 

19  89-66 

1 

20  10-34 

4 

20  31-01!   £ 

20  51-68 

953 

19  70-03 

963 

19  90'70 

973 

20  11-37 

983' 

20  82-04  993 

20  52-71 

i 

19  71-06 

i 

19  91-73 

£ 

20  12-40 

i 

20  33-07    i 

20  53-75 

954 

19  72-09 

964 

19  9276 

974 

20  13-44 

984 

20  34-11  994" 

20  54-78 

^ 

19  73-13 

£ 

19  93-80 

i 

20  14-47 

A 

20  35-14 

i 

20  55-81 

955 

19  74-16 

965 

19  94-83 

975" 

20  15-50  985" 

20  36-18  >995"  20  56-85 

1 

19  75-19 

i 

19  95-87 

£ 

20  16-54 

£ 

20  37-21    £ 

20  57-88 

956" 

19  76-23  1966 

19  96-90 

976 

20  17-57 

986 

20  38-24  996  20  58*91 

i 

19  77-26]   £ 

19  97-93 

£ 

20  18-60 

£ 

20  39-281   ^20  59-95 

957 

19  78-29 

967 

19  98-97 

977 

20  19-64 

987 

20  40-31  997"  20  60-98 

£ 

19  79-33 

1 

20  00-00 

£20  20-67 

£ 

20  41-34    £  20  62-02 

958  19  80-36 

968 

20  01-03 

978  20  21-70 

988  20  42'38  :998  20  63-05 

i 

19  81-40 

£ 

20  0207 

42022-74    £2043-41!   42064-08 

959" 

19  82-43 

!969 

20  03  10 

979"  [20  23-77 

989  20  44-44 

999  20  65-12 

£ 

19  83-46  i   420  04-13 

£20  24-81 

£20  45  48 

420  66-15 

I 

ii  1000  20  67-1  S 

INDEX. 


ALU 

A  LUMINIUM,  qual.  determina- 
J\.    tion,  52 
Amalgams  described,  136 
Ammonia,  33 

—  carbonate  of,  33 
Ammonium,  sulphide  of,  33 
Anthracite,  172 

Antimony,  qual.  determination,  65, 

56 

Anvil,  steel,  23 
Aragonite,  49 
Argentiferous  sulphide  of  copper, 

98 

Argentite,  97 
Argol,  33 
Arsenic,  metallic,  33 

—  qual.  determination,  80-82 
Assay    balance,    description    and 

capacity,  17,  18 

—  grain  weights,  18 

Attwood,  Melville,   on  the  batea, 

29,  30 
Azurite,  146 


BALANCE  for  large  quantities 
and  capable  of  weighing  32 
oz.,  19-22 

—  experiments  with  large,  22 
Barium,  qual.  determination,  47 
Batea,  29-32 

Beaker  glasses,  28 

Berthier,  on  the  heating  power  in 
coals,  174,  175 

Berzelius,  on  the  form  of  blow- 
pipe, 4 

—  on  the  blowpipe  lamp,  7 


BRO 

Berzelius,  on  preparing  pure  iron, 
39 

—  on  fluorine,  75 

—  on  chlorine,  75 

—  on  bromides  and  chlorides,  77 

—  on  palladium  oxides,  89 
Bismuth,  pure,  how  to  make,  38 

—  qual.  determination,  68,  69 

—  native,  153 

—  ores,  153 

—  sulphide,  153 

—  carbonate  of,  153 

—  acicular,  153 

—  blende,  153 

—  metallic    description    of,    153, 

154 

—  assay,   a    previous    qualitative 

examination,  154 

roasting  and  fusing,  155 

Blowpipe  capabilities,  3 

—  description,  4 

—  tips,  4 

—  mouthpiece,  4 

—  how  to  use  it,  5 
-  fuel,  6 

Bone  ash,  33 

Boracic  acid,  33 

Borax,  32 

Borers  for  charcoal,  24,  25 

Bornite,  146 

Boron,  qual.  determination,  83 

Bottle  for  washing  precipitates,  i"J 

—  drop,  for  holding  acids,  29 

Bournonite,  146 

Bromine,  qual.  determination,  76, 

77 
Bromyrite,  98 


206 


INDEX 


BEU 

Brucite,  51 

Brush,  on  blowpipe  gas  lamp,  10 


/CADMIUM,  qual.  determination. 
\J    65,  66 

Cassium,  qual.  determination,  47 
Calcium,  qual.  determination,  49, 

50 

Calomel,  135 
Capsules,  mixing,  26 
Carbon,   qual.  determination,   82, 

83 

Cassiterite,  166 
Cerargyrite,  98 
Cerium,  qual.  determination,  89, 

90 

Chalcopyrite,  146 
Charcoal  as  a    blowpipe  support, 

12 

—  holder,  27 
Chilenite,  98 
Chlorine,  qual.  determination,  75, 

76 

Chromium,  qual. determination,  57 
Cinnabar,  135 
Coal,  description  of,  and  probablt 

origin,  and  where  found,  171. 

172 

—  hard  (hard  coal),  172 

—  brown  (brown  coal),  172 

—  caking  (caking  coal),  172 

—  non-caking  (non-caking  coal), 
172 

—  cannel  (cannel  coal),  172,  173 

—  assay,  moisture  determinatior , 

173 

—  coke  production,  173 

—  the  amount  of  ash,  174 
heating    power  determina 

tion,  174 

—  sulphur  estimation,  175,  17( 
Cobalt,  qual.  determination,  61,  61 

—  nitrate  of,  33 

—  ores,  164 

-  assay,  164,  165 

Cobaltite,  164 

Columbium,   qual.  determinatior, 

91,  92 
Copper  oxide,  33 

—  sulphate  of,  33 


FLA 

Copper,  pure,  how  to  make,  37 

—  qual.  determination,  66 

—  native,  145 

—  glance,  146 

—  red,  146 

—  phosphate  of,  146 

—  arseniate  of,  146 

—  assay,  classification,  146] 
description  of  method  adopt- 
ed to  extract  the  metal  from 
its  matrix,  146,  147 

roasting  the  ore,  147,  148 

fusion  of  the  roasted  ore  or 

product,  Class  B,  148,  149 

refining  the  copper  and  lead 

alloy,  Class  C  (a),  149 

alloy  of  copper  and  anti- 
mony, 150 

Covelline,  146 

Cupel  mould,  29 

Cupellation,  method  of,  106-108 

Cupels,,  how  to  make  them,  29 

Cyanosite,  146 

Cylinder,  hard-wood,  for  preparing 
soda-paper  cornets,  27 


DIDYMIUM,   qual.    determina- 
tion, 90,  91 

Dishes,  evaporating,  27,  28 
Dolomite,  how  to  distinguish  from 

ordinary  limestone,  51,  52 
Domeykite,  14G 

Domeyko,  on  the  assay  of  mer- 
cury, 143-145 


TWBOLITE,  981 
Jj     Epsomite,  51 
Erbium,  qual.  determination,  91 
Erythrite,  164 

Explanation    of     American    gold 
table,  192-194 


T7AHLEKZ,  98,  146 
r  Filter  paper,  29 
Fire-clay  crucibles  and  capsules, 

how  to  make  them,  15,  16 
Flames,  oxidising  and  reducing, 

10 


INDEX 


207 


FLE 

Fletcher,  paraffin  lamp,  9,  10 
Fluorine,  qual.  determination,  75 
Forbes,  David,  on  colours  of  sub- 
limates on  charcoal,  43,  44 

on  the  determination  of  the 

silver  globule  obtained  by  cu- 
pellation,  109-116 
Forceps  with  platinum  tips,  25 

—  brass,  25 

—  iron,  25 
Franklinite,  160 

Fuchs,  on  detection  of  oxygen,  73 

Funnels,  glass,  28 

Furnace,  description  of  the  char- 
coal furnace  and  holder  em- 
ployed in  the  distillation  of 
mercury  and  in  the  assays  of 
gold,  silver,  lead,  &c.,  142-144 


GAHN  on  the    construction  of 
the  blowpipe,  4 
Gold,  pure,  how  to  make,  35 

—  qual.  determination,  56 

—  native,  its  forms  and  places  of 

occurrence,  125 

—  alloys,  native  and  artificial,  126 

—  assay,  explanation  of  the  me- 

thods of  assaying,  126,  127 

classification  of,  127 

of  free  milling  ores,  Class 

A  O),  127,  128 

of  pyrites,  Class  A  (J),  128 

of  river  and  ocean  sands, 

Class  A  O),  128,  129 
of    alluvial    deposits    and 

placer  washings,  Class  A  (d\ 

129 

of  slags,  Class  ,4  0),  ]  30 

of  sweeps,'  Class  A  (/),  130 

• universal  method  for    ores 

and  minerals,  Class  A  (#),  130 
of    alloys,    coins,    and    fine 

gold,  Class  B  O),  130-132 
quantity  of  lead  required  to 

cupel    different    qualities  of 

gold,  131 
separation  from  silver,  131, 

132 

of  dust  and  nuggets,  132 

« in  copper  plates,  133 


ISO 

Gold'assay  when  more  than  10  per 

cent,  of  platinum  is  present, 

133 

• containing  iridium,  133 

when  palladium  is  present, 

and  not  more    than   10  per 

cent,  of  platinum,  133 
when  platinum  and  silver 

are  present,  133,  134 
when  rhodium   is    present, 

134 
—  with   mixed  metals,   as   in 

Class  B  (i),  134 
a    rapid    assay     of     coins, 

nuggets,  &c.,  Class  B  (7),  134, 

135 

amalgams,  135 

Glucinum, qual.  determination,  84, 

85 
Graphite,  33 


HAMMER,  steel,  for  breaking 
rocks,  &c.,  22 

for  flattening  metallic  but- 
tons, 23 

Hanks,  Henry,  on  the  batea,  31,  32 

Hessite,  98 

Holder,  platinum  wire,  14 

Hydrochloric  acid,  33 

Hydrogen,  qual.  determination, 
73,  74 

Hydromagnesite,  51 


TLMENITE,  160 

I   Indium, qual.  determination,  68 

lodyrite,  98 

Iodine,  qual.  determination,  77 

Iridium,  qual.  determination,  93 

—  estimation  of,  133 

Iron,  pure,  how  to  make,  39,  40 
-  protosulpbate,  33 

—  qual.  determination,  57-61 

—  native,  159 

—  sulphides,  159 

—  ores,  159 

—  ore,  brown,  159 

—  carbonate  of,  160 

—  assay,  description  of  the  me- 

thods adopted,  160-163 


208 


INDEX. 


KUP 
TTUPFERNICKEL,  163 

jy 

T  AMBOKN,  on  blowpipe  flames, 

_L     10-12 

Lamp,  used  by  Plattner,  7 

—  for  burning  alcohol,  9 

—  for  burning  paraffin,  9 

—  using  gas  according  to  Brush,  10  j 
Lanthanum,  qual.  determination, 

85,86 
Lead  oxychloride,  33 

—  pure,  how  to  make,  36 

—  qual.  determination,  66-68 

—  native,  150 

—  ores,  150 

—  assay,  classification  of,  151 
method  employed  and  results 

obtained  by  same,  151 

preparation  of  sample  and 

instructions  in  fusion,  &c.,  151, 
152 

of  Class  By  152 

Lignite,  172 

Litharge,  33 

Lithia,  Turner's  method  »f  detect- 
ing, 72 

Lithium,  qual.  determination,  72, 
73 

Litmus  paper,  33 


MAGNESITE,  51 
Magnesium  wire,  33 

—  qual.  determination,  50-52 
Magnet,  steel,  24 

Makins,  on  the  fusing  power  of 

the  blowpipe,  3 
Malachite,  146 
Manganese,  qual.  determination, 

52-54 

Menaccanite,  160 
Mercury,  pure,  how  to  make,  38,  39 

—  qual.  determination,  71 

—  description  and  occurrence  of, 

135 

—  assay,  classification  of,  136,  137 
preparation  and  description 

of  method  adopted  and  mode 
of  making  retorts  to  determine 
Class  A,  137-139 


NIT 

Mercury  assay  of  Class  7?,  139 

amalgams  that  spurt  on  heat 

being  applied,  140 

of  amalgams,  140-143 

description  of  the  steel 

retorts,  distillation  pipe,  re- 
ceiver, &c.,  141,  142 

Millerite,  163 

Mitchell,  on  estimation  of  sulphur 
in  coal,  175,  176 

Molybdenum,  qual.  determination, 
92,  93 

Mortar,  steel,  23 

—  agate,  23 


NICKEL,  oxalate  of,  33 
—  qual.  determination,    62, 
63 

—  ores,  163 

—  white  (white  nickel),  163 

—  antimonial,  163 
-glance,  163 

—  copper  (copper  nickel),  163 

—  assay,  163,  164 

—  and  cobalt  assays,  the  method 

adopted,  165,  166 

assay  classification  of ,  166 

roasting,  166 

fusing  with    metallic 

arsenic,  166,  167 
nickel,  cobalt,  arsenic, 

and  iron,  167,  168 
separating  the  cobalt 

from  the  nickel  by  slagging, 

168,  169 
ores  and  products  in 

which  nickel,  cobalt,  copper, 

and  iron  are  combined  with  a 

small  quantity  of  arsenic,  169, 

170 
when  nickel,   cobalt, 

iron,     and    copper,    &c.,  are 

present,  170,  171 
alloys  of  copper  and 

nickel,  171 
poor  ores  requiring  a 

collecting  agent,  171 
Niobium,  qual.  determination,  91 
Nitre,  33 
Nitric  acid,  33 


INDEX. 


209 


NIT 

Nitrogen,  qual.  determination,  74 
Nitrous  acid,  33 

OSMIUM,    qual.   determination, 
93 
Oxygen,   qual.  determination,  73 

"PALLADIUM,  qual.  determina- 
JL      tion,  88,  89 

Pan,  used  with  large  balance,  21 
Pans,  horn,  19 

—  metal,  19 

Paper  prepared  for  making  cornets 

in  the  silver  and  gold  assays, 

29 

Pentlandite,  163 
Periclase,  51 
Phillips,  J.  A.,  on  occurrence  of 

tin,  156 
Phosphorus,  qual.   determination, 

78-80 

Phosphorus  salt,  32 
Platinum  foil,  13 

—  wire,  13 

instructions  how  to  use  it,  14 

—  spoons,  15 

—  qual.  determination,  71 
Plattner,  on  blowpipe  lamp,  7 

—  on  iron  compounds,  59 

—  on  detecting  cobalt  in  nickel 

alloys,  62 

—  on  detecting  a  small  quantity 

of  nickel  in  oxides  of  cobalt, 
manganese,  and  iron,  63 

—  on  lithia,  72 

—  on  sulphur,  78 

—  on  sesquioxide  of  iron,  162 
Pliers,  steel,  26 
Polybasite,  98 

Potash,  caustic,  33 

—  carbonate  of,  33 
Potassa,  neutral  oxalate  of,  32 
-  bisulphate  of,  33 

Potassium,  cyanide  of,  32 

—  qual.  determination  of,  45,  46 
Proustite,  97 

Pyrargyrite,  97 


Q 


UAETZ,  33 


SIL 

T)HODIUM,qual.  determination, 
XI    93 

Riders  gold,  19 
Roach,  John,  on  the  batea,  30 
Rubidium,  qual.  determination,  47 
Ruthenium,  qual.  determination,  89 


SALT,  common,  33 
Saw  for  cutting  charcoal,  13 
Scorifier,  104 
Screens,  punched,  27 
Selenic  silver,  98 
Selenium,  qual.  determination,  93, 

94 

Shears,  cutting,  25 
Sieves,  wire,  27 
Silicium,  qual.  determination,  83, 

84 
Silver,  pure,  how  to  make,  34 

—  qual.  determination,  56 

—  native,  97 

—  in  sea  water,  97 

—  minerals  and  ores,  97,  98 

—  in  products  and  refuses,  98 

—  explanation     of    the     modus 

operandi  employed  in  assay- 
ing its  ores  and  compounds,  99 

—  assay,  classification,  99, 100 

—  amount  of  lead  required  for 
different  ores,  101,  102 

preparation  of  the  ore  and 

the  reduction  to  silver  lead, 
100-104 

how  to  scorify  and  concen- 
trate the  silver  lead,  104-106 

—  of   argentiferous    molybde- 
nite, 119,  120 

of  Class  A  (c),  120 

of  Class  A  (d),  120,  121 

—  of  Class  A  (0),  being  a  gene- 
ral   method  adapted  to  the 
assay  of  silver  ores,  121,  122 

of  Class  B  (a),  being  alloys 

ready  for  cupellation,  122, 
123 

of  alloys  requiring  cleansing 

before  cupellation,  123 

—  of  alloys  and  quantity  of  test 
lead  required,  123 

of  amalgams,  123 


210 


INDEX. 


SIL 

Silver  assay,  determination  in  brass 
and  black  copper,  123,  124 

—  - —  in  antimony,  tellurium,  and 

zinc,  124 
in  tin  and  gun  metal,  124 

—  - —  in  silver-steel  and  iron,  124, 

125 
in  alloys  of  lead  or  bismuth, 

125 
in  copper  coins,  wire,   and 

cement,  125 
Skutterudite,  164,  165 
Smaltine,  164 

Smyth,  W.W.,  Prof.,  on  the  batea,  31 
Soda,  carbonate  of,  32 
Sodium,  qual.  determination,  46, 47 
Spar,  fluor,  33 
Spoon,  horn,  24 

—  ivory,  for  mixing,  27 
Stand  to  hold  cupels,  27 
Stein,  on  nitrogen,  74 
Stephanite,  97 
Sternbergite,  98 

Strontium,    qual.    determination, 

48,49 
Sublimates  on  charcoal,  colour, 

43,  44 
Sulphur,  roll,  33 

—  qual.  determination,  77,  78 
Sulphuric  acid,  33 
Synthetical  assays,  109 


HHABLE  for  calculating  the  gold 
JL    and  silver  in  a  ton  of  2,240  Ibs., 

117,  118 

—  for  calculating  the  gold  and 

silver  in  a  ton  of  2,000  Ibs., 

118,  119 

—  of  English  Mint  value  of  gold, 

179-191. 

—  of  the  value  of  gold  in  the  United 

States  of  America,  195-205 
Tantalum,    qual.     determination, 

86,  87 

Tellurium,  qual.  determination,  94 
Terbium,  qual.  determination,  86 
Thallium,  qual.  determination,  92 


ZIE 

Thorium,  qual.  determination,  92 

Tiemannite,  135 

Tin,  pure,  how  to  make,  37 

—  qual.  determination,  55 

—  metallic,  156 

—  assay,  classification  of,  156 

—  oxides,  156 

—  assay,  fusion  of  pure  oxides,  157 
—  ores  containing  silica,  157, 

158 

-  —  when  sulphur,  arsenic,  and 
tungsten  are  present,  158,  159 

—  —   ores    with  less  than  5  per 

cent,,  159 
Titanium,     qual.    determination, 

69-71 

Tubes,  glass,  open  at  both  ends,  1  6 
--  closed  and  bulb  -shaped,  17 
--  test,  for  parting  gold  and 

silver,  28 
Tungsten,  qual.  determination,  87, 

88 
Turner,  on  lithia,  72 

—  on  boron,  83 

URANIUM,  qual.  determination, 
87 

Ure,  Dr.,  on  Berthier's  process  of 
determining  absolute  heating 
power,  175 

VALUE  of  gold  coins  in  the 
United  States  of  America, 
191,  192 

Vanadium,  qual.  determination,  88 
Von  Kobell,  on  tungstite,  87 

TT70LFSBERGITE,  146 
VV      Wollastonite,  49 

TTTTRIUM,  qual.  determination, 
I      86 


on      distinguishing 
i  1    limestones,  51 
Zinc,  qual.  determination,  63,  64 
Zirconium,  qual.  determination,  94 


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C.E      Illustrated. 


D.   VAN  NOSTRAND. 


Xin.  A  PRACTICAL  TREATISE  ON  THE  GASES  MET  WITH  IN  COAL 
MINES.  By  the  late  J.  J.  ATKINSON,  Government  Inspector  of 
Mines  for  the  County  of  Durham,  England. 

XIV.  FRICTION  OF  AIR  IN  MINES.    By  J.  J.  ATKINSON,  author  of  "  A 
Practical  Treatise  on  the  Gases  met  with  in  Coal  Mines." 

XV.  SKEW  ARCHES.      By  Prof.  E.   W.  HYDE,  C.E.    Illustrated  with 
numerous  engravings  and  three  folded  plates. 

XVI.  A  GRAPHIC  METHOD  FOR  SOLVING  CERTAIN  ALGEBRAIC  EQUA- 
TIONS.    By  Prof.  GEORGE  L.  VOSE.     With  Illustrations. 

XVII.  WATER   AND   WATER   SUPPLY.      By  Prof.  W.  H.  CORFIELD, 
M.A.,  of  the  University  College,  London. 

XVIII.  SEWERAGE    AND    SEWAGE    UTILIZATION.      By  Prof.   W.   H. 
CORFIELD,  M.A.,  of  the  University  College,  London. 

tTX.  STRENGTH  OF  BEAMS  UNDER  TRANSVERSE  LOADS.  By  Prof. 
W.  ALLAN,  author  of  "Theory  of  Arches."  With  Illustrations 

XX.  BRIDGE  AND  TUNNEL  CENTRES.       By  JOHN  B.  McMASTER8» 
C.E.    With  Illustrations. 

XXI.  SAFETY  VALVES.    By  RICHARD  H.  BUEL,  C.E.    With  Illustra- 
tions. 

XXH.  HIGH  MASONRY  DAMS.  By  JOHN  B.  MCMASTERS,  C.E. 
With  Illustrations. 

XXIH.  THE  FATIGUE  OF  METALS  under  Repeated  Strains,  with 
various  Tables  of  Results  of  Experiments.  From  the  Germac  of 
Prof.  LUDWIG  SPANGENBERG.  With  a  Preface  by  S.  H.  SHRKVE, 
A.M .  With  Illustrations. 

XXIV.  A   PRACTICAL  TREATISE  ON  THE  TEETH  OF  WHEELS,  with 
the  theory  of  the  use  of  Robinson's  Odontograph.    By  S.  W.  ROBIN- 
BON,  Prof,  of  Mechanical  Engineering,  Illinois  Industrial  University. 

XXV.  THEORY   AND    CALCULATIONS  OF  CONTINUOUS  BRIDGES.    By 
MANSFIELD  MERRIMAN,  C.E.     With  Illustrations. 

XXVI.  PRACTICAL   TREATISE  ON  THE   PROPERTIES    OF  CONTINUOUI 
BRIDGES.     By  CHARLES  BENDER,  C.E. 


24  D.    VAN  SOSTRAND. 


XXVII.  ON  BOILER  INCRUSTATION  AND  CORROSION.     By  F.  J.  ROWAN. 
With  Illustrations. 

XXVIII.  ON  TRANSMISSION  OF  POWER  BY  WIRE  ROPE.      By  ALBERT 
W.  SrAHL.     With  Illustrations. 

XXIX.  INJECTORS.     The  Theory  and  Use.     Translated  from  the  French 
of  M.  LEON  POCHET.     With  Illustrations. 

XXX.  TERRESTRIAL  MAGNETISM  AND  THE  MAGNETISM  OF  IRON  SHIPS. 
By  Prof.  FAIRMAN  ROGERS.     With  Illustrations. 

XXXI.  THE  SANITARY  CONDITION  OF  DWELLING   HOUSES  IN  TOWN 
AND  COUNTRY.     By  GEORGE  E.  WARING,  Jr.     With  Illustrations, 

XXXII.  CABLE  MAKING  OF  SUSPENSION  BRIDGES  A£  EXEMPLIFIED  IN 
THE   EAST   RIVER  BRIDGE.     By  WILHELM   HILDENBRAND,  C.   E. 
With  Illustrations. 

XXXIII.  MECHANICS  OF  VENTILATION.     By  GEORGE  W.  RAFTER,  Civil 
Engineer. 

XXXIV.  FOUNDATIONS.     By  Prof.  JULES  GAUDARD,  C.  E.     Translated 
from  the  French,  by  L.  F.  VERNON  HARCOURT,  M.  I.  C.  E. 

XXXV.  THE  ANEROID  BAROMETER,  ITS  CONSTRUCTION  AND  USE.    Com- 
piled by  Prof.  GEORGE  W.  PLYMPTON.     Illustrated. 

XXXVI.  MATTER  AND  MOTION.     By  J.  CLERK  MAXWELL,  M.  A. 

XXXVII.  GEOGRAPHICAL  SURVEYING.     Its  Uses,  Methods  and  Results. 
By  FRANK  DE  YEAUX  CARPENTER,  C.  E. 

XXXVIII.  MAXIMUM  STRESSES  IN  FRAMED  BRIDGES.      By  Prof.  WM. 
CAIN,  A.  M.,  C.  E.     Illustrated. 

XXXIX.  A   HAND  BOOK   OF   THE   ELECTRO   MAGNETIC  TELEGRAPH. 
By  A.  E.  LORING.     Illustrated. 

XL.     TRANSMISSION   OF  POWER   BY    COMPRESSED    AIR.       By    ROBERT 
ZAHNER,  M.  E.     Illustrated. 

XL1       ON  THE  STRENGTH  OF  MATERIALS.     By  WM.  KENT,  C.  E. 
XLIII.     WAVE  AND  VORTEX  MOTION.     By  Dr.  THOMAS  CRAIG. 


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